Help to calculate the integral $int 314^{cos x} ; dx$
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I stopped at the place highlighted in yellow how to find this integral ? $$int (314)^{large cos x} ; dx$$
$$begin{aligned}int 314^{cos x}sin x,mathrm{d}x=&int umathrm{d}v=uv-int vmathrm{d} u\
&u=sin xquadmathrm{d}u=cos xmathrm{d}x\
&mathrm{d}v=314^{cos x}mathrm{d}xquad v=int 314^{cos x}mathrm{d}x
end{aligned}$$
calculus integration indefinite-integrals
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add a comment |
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I stopped at the place highlighted in yellow how to find this integral ? $$int (314)^{large cos x} ; dx$$
$$begin{aligned}int 314^{cos x}sin x,mathrm{d}x=&int umathrm{d}v=uv-int vmathrm{d} u\
&u=sin xquadmathrm{d}u=cos xmathrm{d}x\
&mathrm{d}v=314^{cos x}mathrm{d}xquad v=int 314^{cos x}mathrm{d}x
end{aligned}$$
calculus integration indefinite-integrals
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This is not an integral to do by parts.
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– T. Bongers
Dec 10 '18 at 17:22
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Your by-parts integration is wrong.
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– Yves Daoust
Dec 10 '18 at 17:31
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The integrals $int a^{cos x} dx$ do not have solutions in terms of elementary functions in general, but the original integral in the image does using the substitution $u = cos x$ as indicated by the answer below.
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– JavaMan
Dec 10 '18 at 17:33
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Please use mathjax to format your equations next time so we don't have to do it for you
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– Jam
Dec 10 '18 at 17:51
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The "art" of integration by parts is to substitute $u$ for something buried deeply within something and to balance that with $dv$ being something easy and expandible on the surface. You choice that $u = sin x $ and $dv = 314^{cos x}dx$ is the exact opposite if that. Try $dv= sin x$ so $v =-cos x$ and $u=314{-v}$ and $int 314^{cos x} dx = int u dv = int 314^{-v} dv$. (ALthough switching the negatives so $v=cos x$ and $int - 314^{v}dv$ will be easier.
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– fleablood
Dec 10 '18 at 17:53
add a comment |
$begingroup$
I stopped at the place highlighted in yellow how to find this integral ? $$int (314)^{large cos x} ; dx$$
$$begin{aligned}int 314^{cos x}sin x,mathrm{d}x=&int umathrm{d}v=uv-int vmathrm{d} u\
&u=sin xquadmathrm{d}u=cos xmathrm{d}x\
&mathrm{d}v=314^{cos x}mathrm{d}xquad v=int 314^{cos x}mathrm{d}x
end{aligned}$$
calculus integration indefinite-integrals
$endgroup$
I stopped at the place highlighted in yellow how to find this integral ? $$int (314)^{large cos x} ; dx$$
$$begin{aligned}int 314^{cos x}sin x,mathrm{d}x=&int umathrm{d}v=uv-int vmathrm{d} u\
&u=sin xquadmathrm{d}u=cos xmathrm{d}x\
&mathrm{d}v=314^{cos x}mathrm{d}xquad v=int 314^{cos x}mathrm{d}x
end{aligned}$$
calculus integration indefinite-integrals
calculus integration indefinite-integrals
edited Dec 10 '18 at 17:51
Jam
4,98521431
4,98521431
asked Dec 10 '18 at 17:21
АлександрАлександр
61
61
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This is not an integral to do by parts.
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– T. Bongers
Dec 10 '18 at 17:22
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Your by-parts integration is wrong.
$endgroup$
– Yves Daoust
Dec 10 '18 at 17:31
$begingroup$
The integrals $int a^{cos x} dx$ do not have solutions in terms of elementary functions in general, but the original integral in the image does using the substitution $u = cos x$ as indicated by the answer below.
$endgroup$
– JavaMan
Dec 10 '18 at 17:33
$begingroup$
Please use mathjax to format your equations next time so we don't have to do it for you
$endgroup$
– Jam
Dec 10 '18 at 17:51
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The "art" of integration by parts is to substitute $u$ for something buried deeply within something and to balance that with $dv$ being something easy and expandible on the surface. You choice that $u = sin x $ and $dv = 314^{cos x}dx$ is the exact opposite if that. Try $dv= sin x$ so $v =-cos x$ and $u=314{-v}$ and $int 314^{cos x} dx = int u dv = int 314^{-v} dv$. (ALthough switching the negatives so $v=cos x$ and $int - 314^{v}dv$ will be easier.
$endgroup$
– fleablood
Dec 10 '18 at 17:53
add a comment |
$begingroup$
This is not an integral to do by parts.
$endgroup$
– T. Bongers
Dec 10 '18 at 17:22
$begingroup$
Your by-parts integration is wrong.
$endgroup$
– Yves Daoust
Dec 10 '18 at 17:31
$begingroup$
The integrals $int a^{cos x} dx$ do not have solutions in terms of elementary functions in general, but the original integral in the image does using the substitution $u = cos x$ as indicated by the answer below.
$endgroup$
– JavaMan
Dec 10 '18 at 17:33
$begingroup$
Please use mathjax to format your equations next time so we don't have to do it for you
$endgroup$
– Jam
Dec 10 '18 at 17:51
$begingroup$
The "art" of integration by parts is to substitute $u$ for something buried deeply within something and to balance that with $dv$ being something easy and expandible on the surface. You choice that $u = sin x $ and $dv = 314^{cos x}dx$ is the exact opposite if that. Try $dv= sin x$ so $v =-cos x$ and $u=314{-v}$ and $int 314^{cos x} dx = int u dv = int 314^{-v} dv$. (ALthough switching the negatives so $v=cos x$ and $int - 314^{v}dv$ will be easier.
$endgroup$
– fleablood
Dec 10 '18 at 17:53
$begingroup$
This is not an integral to do by parts.
$endgroup$
– T. Bongers
Dec 10 '18 at 17:22
$begingroup$
This is not an integral to do by parts.
$endgroup$
– T. Bongers
Dec 10 '18 at 17:22
$begingroup$
Your by-parts integration is wrong.
$endgroup$
– Yves Daoust
Dec 10 '18 at 17:31
$begingroup$
Your by-parts integration is wrong.
$endgroup$
– Yves Daoust
Dec 10 '18 at 17:31
$begingroup$
The integrals $int a^{cos x} dx$ do not have solutions in terms of elementary functions in general, but the original integral in the image does using the substitution $u = cos x$ as indicated by the answer below.
$endgroup$
– JavaMan
Dec 10 '18 at 17:33
$begingroup$
The integrals $int a^{cos x} dx$ do not have solutions in terms of elementary functions in general, but the original integral in the image does using the substitution $u = cos x$ as indicated by the answer below.
$endgroup$
– JavaMan
Dec 10 '18 at 17:33
$begingroup$
Please use mathjax to format your equations next time so we don't have to do it for you
$endgroup$
– Jam
Dec 10 '18 at 17:51
$begingroup$
Please use mathjax to format your equations next time so we don't have to do it for you
$endgroup$
– Jam
Dec 10 '18 at 17:51
$begingroup$
The "art" of integration by parts is to substitute $u$ for something buried deeply within something and to balance that with $dv$ being something easy and expandible on the surface. You choice that $u = sin x $ and $dv = 314^{cos x}dx$ is the exact opposite if that. Try $dv= sin x$ so $v =-cos x$ and $u=314{-v}$ and $int 314^{cos x} dx = int u dv = int 314^{-v} dv$. (ALthough switching the negatives so $v=cos x$ and $int - 314^{v}dv$ will be easier.
$endgroup$
– fleablood
Dec 10 '18 at 17:53
$begingroup$
The "art" of integration by parts is to substitute $u$ for something buried deeply within something and to balance that with $dv$ being something easy and expandible on the surface. You choice that $u = sin x $ and $dv = 314^{cos x}dx$ is the exact opposite if that. Try $dv= sin x$ so $v =-cos x$ and $u=314{-v}$ and $int 314^{cos x} dx = int u dv = int 314^{-v} dv$. (ALthough switching the negatives so $v=cos x$ and $int - 314^{v}dv$ will be easier.
$endgroup$
– fleablood
Dec 10 '18 at 17:53
add a comment |
4 Answers
4
active
oldest
votes
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Hint: Substitute $$t=cos(x)$$ then $$dt=-sin(x)dx$$Then you will get $$-int 314^t dt$$
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But its $ dx$ how to complete the rest?
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– lab bhattacharjee
Dec 11 '18 at 7:48
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it is $$dt=-sin(x)dx$$ what do you mean with the rest?
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– Dr. Sonnhard Graubner
Dec 11 '18 at 8:33
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$$int314^{cos x} dx=-intdfrac{314^t dt}{sin x}$$ right?
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– lab bhattacharjee
Dec 11 '18 at 8:40
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I thought your integral is $$int 314^{cos(x)}sin(x)dx$$
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– Dr. Sonnhard Graubner
Dec 11 '18 at 8:42
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Where have you find this $$int314^{cos x}sin x dx$$
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– lab bhattacharjee
Dec 11 '18 at 8:43
|
show 3 more comments
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$int314^{cos x}~dx$
$=int e^{cos x}ln314~dx$
$=ln314intsumlimits_{n=0}^inftydfrac{cos^{2n}x}{(2n)!}dx+ln314intsumlimits_{n=0}^inftydfrac{cos^{2n+1}x}{(2n+1)!}dx$
$=ln314intleft(1+sumlimits_{n=1}^inftydfrac{cos^{2n}x}{(2n)!}right)dx+ln314intsumlimits_{n=0}^inftydfrac{cos^{2n+1}x}{(2n+1)!}dx$
For $n$ is any natural number,
$intcos^{2n}x~dx=dfrac{(2n)!x}{4^n(n!)^2}+sumlimits_{k=1}^ndfrac{(2n)!((k-1)!)^2sin xcos^{2k-1}x}{4^{n-k+1}(n!)^2(2k-1)!}+C$
This result can be done by successive integration by parts.
For $n$ is any non-negative integer,
$intcos^{2n+1}x~dx$
$=intcos^{2n}x~d(sin x)$
$=int(1-sin^2x)^n~d(sin x)$
$=intsumlimits_{k=0}^nC_k^n(-1)^ksin^{2k}x~d(sin x)$
$=sumlimits_{k=0}^ndfrac{(-1)^kn!sin^{2k+1}x}{k!(n-k)!(2k+1)}+C$
$thereforeln314intleft(1+sumlimits_{n=1}^inftydfrac{cos^{2n}x}{(2n)!}right)dx+ln314intsumlimits_{n=0}^inftydfrac{cos^{2n+1}x}{(2n+1)!}dx$
$=xln314+ln314sumlimits_{n=1}^inftydfrac{x}{4^n(n!)^2}+ln314sumlimits_{n=1}^inftysumlimits_{k=1}^ndfrac{((k-1)!)^2sin xcos^{2k-1}x}{4^{n-k+1}(n!)^2(2k-1)!}+ln314sumlimits_{n=0}^inftysumlimits_{k=0}^ndfrac{(-1)^kn!sin^{2k+1}x}{(2n+1)!k!(n-k)!(2k+1)}+C$
$=ln314sumlimits_{n=0}^inftydfrac{x}{4^n(n!)^2}+ln314sumlimits_{n=1}^inftysumlimits_{k=1}^ndfrac{((k-1)!)^2sin xcos^{2k-1}x}{4^{n-k+1}(n!)^2(2k-1)!}+ln314sumlimits_{n=0}^inftysumlimits_{k=0}^ndfrac{(-1)^kn!sin^{2k+1}x}{(2n+1)!k!(n-k)!(2k+1)}+C$
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add a comment |
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The whole point of substitution by parts is to substitute.
You are trying to find
$int 314^{cos x} sin x dx$.
If you substitute $u = cos x$ then $314^{cos x}$ becomes $314^u$.
And $du = -sin x dx$ so $sin x dx$.
So $int 314^{cos x} sin x dx = int -314^{u}du$.
And as $sin a^x dx = frac {a^x}{ln a} + C$
We have $int 314^{cos x} sin x dx = int -314^{u}du= -frac {314^u}{ln 314} = -frac {314^{cos x}}{ln 314}$
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2
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Why are you calling this substitution by parts? This is just substitution... The whole point of integration by parts is to undo the product rule.
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– JavaMan
Dec 10 '18 at 17:44
add a comment |
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By parts,
$$int 314^{cos x}sin x,dx=-314^{cos x}cos x-log314int 314^{cos x}sin^2x,dx$$
leads you about nowhere.
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add a comment |
Your Answer
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4 Answers
4
active
oldest
votes
4 Answers
4
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
Hint: Substitute $$t=cos(x)$$ then $$dt=-sin(x)dx$$Then you will get $$-int 314^t dt$$
$endgroup$
$begingroup$
But its $ dx$ how to complete the rest?
$endgroup$
– lab bhattacharjee
Dec 11 '18 at 7:48
$begingroup$
it is $$dt=-sin(x)dx$$ what do you mean with the rest?
$endgroup$
– Dr. Sonnhard Graubner
Dec 11 '18 at 8:33
$begingroup$
$$int314^{cos x} dx=-intdfrac{314^t dt}{sin x}$$ right?
$endgroup$
– lab bhattacharjee
Dec 11 '18 at 8:40
$begingroup$
I thought your integral is $$int 314^{cos(x)}sin(x)dx$$
$endgroup$
– Dr. Sonnhard Graubner
Dec 11 '18 at 8:42
$begingroup$
Where have you find this $$int314^{cos x}sin x dx$$
$endgroup$
– lab bhattacharjee
Dec 11 '18 at 8:43
|
show 3 more comments
$begingroup$
Hint: Substitute $$t=cos(x)$$ then $$dt=-sin(x)dx$$Then you will get $$-int 314^t dt$$
$endgroup$
$begingroup$
But its $ dx$ how to complete the rest?
$endgroup$
– lab bhattacharjee
Dec 11 '18 at 7:48
$begingroup$
it is $$dt=-sin(x)dx$$ what do you mean with the rest?
$endgroup$
– Dr. Sonnhard Graubner
Dec 11 '18 at 8:33
$begingroup$
$$int314^{cos x} dx=-intdfrac{314^t dt}{sin x}$$ right?
$endgroup$
– lab bhattacharjee
Dec 11 '18 at 8:40
$begingroup$
I thought your integral is $$int 314^{cos(x)}sin(x)dx$$
$endgroup$
– Dr. Sonnhard Graubner
Dec 11 '18 at 8:42
$begingroup$
Where have you find this $$int314^{cos x}sin x dx$$
$endgroup$
– lab bhattacharjee
Dec 11 '18 at 8:43
|
show 3 more comments
$begingroup$
Hint: Substitute $$t=cos(x)$$ then $$dt=-sin(x)dx$$Then you will get $$-int 314^t dt$$
$endgroup$
Hint: Substitute $$t=cos(x)$$ then $$dt=-sin(x)dx$$Then you will get $$-int 314^t dt$$
edited Dec 10 '18 at 17:43
answered Dec 10 '18 at 17:24
Dr. Sonnhard GraubnerDr. Sonnhard Graubner
74.7k42865
74.7k42865
$begingroup$
But its $ dx$ how to complete the rest?
$endgroup$
– lab bhattacharjee
Dec 11 '18 at 7:48
$begingroup$
it is $$dt=-sin(x)dx$$ what do you mean with the rest?
$endgroup$
– Dr. Sonnhard Graubner
Dec 11 '18 at 8:33
$begingroup$
$$int314^{cos x} dx=-intdfrac{314^t dt}{sin x}$$ right?
$endgroup$
– lab bhattacharjee
Dec 11 '18 at 8:40
$begingroup$
I thought your integral is $$int 314^{cos(x)}sin(x)dx$$
$endgroup$
– Dr. Sonnhard Graubner
Dec 11 '18 at 8:42
$begingroup$
Where have you find this $$int314^{cos x}sin x dx$$
$endgroup$
– lab bhattacharjee
Dec 11 '18 at 8:43
|
show 3 more comments
$begingroup$
But its $ dx$ how to complete the rest?
$endgroup$
– lab bhattacharjee
Dec 11 '18 at 7:48
$begingroup$
it is $$dt=-sin(x)dx$$ what do you mean with the rest?
$endgroup$
– Dr. Sonnhard Graubner
Dec 11 '18 at 8:33
$begingroup$
$$int314^{cos x} dx=-intdfrac{314^t dt}{sin x}$$ right?
$endgroup$
– lab bhattacharjee
Dec 11 '18 at 8:40
$begingroup$
I thought your integral is $$int 314^{cos(x)}sin(x)dx$$
$endgroup$
– Dr. Sonnhard Graubner
Dec 11 '18 at 8:42
$begingroup$
Where have you find this $$int314^{cos x}sin x dx$$
$endgroup$
– lab bhattacharjee
Dec 11 '18 at 8:43
$begingroup$
But its $ dx$ how to complete the rest?
$endgroup$
– lab bhattacharjee
Dec 11 '18 at 7:48
$begingroup$
But its $ dx$ how to complete the rest?
$endgroup$
– lab bhattacharjee
Dec 11 '18 at 7:48
$begingroup$
it is $$dt=-sin(x)dx$$ what do you mean with the rest?
$endgroup$
– Dr. Sonnhard Graubner
Dec 11 '18 at 8:33
$begingroup$
it is $$dt=-sin(x)dx$$ what do you mean with the rest?
$endgroup$
– Dr. Sonnhard Graubner
Dec 11 '18 at 8:33
$begingroup$
$$int314^{cos x} dx=-intdfrac{314^t dt}{sin x}$$ right?
$endgroup$
– lab bhattacharjee
Dec 11 '18 at 8:40
$begingroup$
$$int314^{cos x} dx=-intdfrac{314^t dt}{sin x}$$ right?
$endgroup$
– lab bhattacharjee
Dec 11 '18 at 8:40
$begingroup$
I thought your integral is $$int 314^{cos(x)}sin(x)dx$$
$endgroup$
– Dr. Sonnhard Graubner
Dec 11 '18 at 8:42
$begingroup$
I thought your integral is $$int 314^{cos(x)}sin(x)dx$$
$endgroup$
– Dr. Sonnhard Graubner
Dec 11 '18 at 8:42
$begingroup$
Where have you find this $$int314^{cos x}sin x dx$$
$endgroup$
– lab bhattacharjee
Dec 11 '18 at 8:43
$begingroup$
Where have you find this $$int314^{cos x}sin x dx$$
$endgroup$
– lab bhattacharjee
Dec 11 '18 at 8:43
|
show 3 more comments
$begingroup$
$int314^{cos x}~dx$
$=int e^{cos x}ln314~dx$
$=ln314intsumlimits_{n=0}^inftydfrac{cos^{2n}x}{(2n)!}dx+ln314intsumlimits_{n=0}^inftydfrac{cos^{2n+1}x}{(2n+1)!}dx$
$=ln314intleft(1+sumlimits_{n=1}^inftydfrac{cos^{2n}x}{(2n)!}right)dx+ln314intsumlimits_{n=0}^inftydfrac{cos^{2n+1}x}{(2n+1)!}dx$
For $n$ is any natural number,
$intcos^{2n}x~dx=dfrac{(2n)!x}{4^n(n!)^2}+sumlimits_{k=1}^ndfrac{(2n)!((k-1)!)^2sin xcos^{2k-1}x}{4^{n-k+1}(n!)^2(2k-1)!}+C$
This result can be done by successive integration by parts.
For $n$ is any non-negative integer,
$intcos^{2n+1}x~dx$
$=intcos^{2n}x~d(sin x)$
$=int(1-sin^2x)^n~d(sin x)$
$=intsumlimits_{k=0}^nC_k^n(-1)^ksin^{2k}x~d(sin x)$
$=sumlimits_{k=0}^ndfrac{(-1)^kn!sin^{2k+1}x}{k!(n-k)!(2k+1)}+C$
$thereforeln314intleft(1+sumlimits_{n=1}^inftydfrac{cos^{2n}x}{(2n)!}right)dx+ln314intsumlimits_{n=0}^inftydfrac{cos^{2n+1}x}{(2n+1)!}dx$
$=xln314+ln314sumlimits_{n=1}^inftydfrac{x}{4^n(n!)^2}+ln314sumlimits_{n=1}^inftysumlimits_{k=1}^ndfrac{((k-1)!)^2sin xcos^{2k-1}x}{4^{n-k+1}(n!)^2(2k-1)!}+ln314sumlimits_{n=0}^inftysumlimits_{k=0}^ndfrac{(-1)^kn!sin^{2k+1}x}{(2n+1)!k!(n-k)!(2k+1)}+C$
$=ln314sumlimits_{n=0}^inftydfrac{x}{4^n(n!)^2}+ln314sumlimits_{n=1}^inftysumlimits_{k=1}^ndfrac{((k-1)!)^2sin xcos^{2k-1}x}{4^{n-k+1}(n!)^2(2k-1)!}+ln314sumlimits_{n=0}^inftysumlimits_{k=0}^ndfrac{(-1)^kn!sin^{2k+1}x}{(2n+1)!k!(n-k)!(2k+1)}+C$
$endgroup$
add a comment |
$begingroup$
$int314^{cos x}~dx$
$=int e^{cos x}ln314~dx$
$=ln314intsumlimits_{n=0}^inftydfrac{cos^{2n}x}{(2n)!}dx+ln314intsumlimits_{n=0}^inftydfrac{cos^{2n+1}x}{(2n+1)!}dx$
$=ln314intleft(1+sumlimits_{n=1}^inftydfrac{cos^{2n}x}{(2n)!}right)dx+ln314intsumlimits_{n=0}^inftydfrac{cos^{2n+1}x}{(2n+1)!}dx$
For $n$ is any natural number,
$intcos^{2n}x~dx=dfrac{(2n)!x}{4^n(n!)^2}+sumlimits_{k=1}^ndfrac{(2n)!((k-1)!)^2sin xcos^{2k-1}x}{4^{n-k+1}(n!)^2(2k-1)!}+C$
This result can be done by successive integration by parts.
For $n$ is any non-negative integer,
$intcos^{2n+1}x~dx$
$=intcos^{2n}x~d(sin x)$
$=int(1-sin^2x)^n~d(sin x)$
$=intsumlimits_{k=0}^nC_k^n(-1)^ksin^{2k}x~d(sin x)$
$=sumlimits_{k=0}^ndfrac{(-1)^kn!sin^{2k+1}x}{k!(n-k)!(2k+1)}+C$
$thereforeln314intleft(1+sumlimits_{n=1}^inftydfrac{cos^{2n}x}{(2n)!}right)dx+ln314intsumlimits_{n=0}^inftydfrac{cos^{2n+1}x}{(2n+1)!}dx$
$=xln314+ln314sumlimits_{n=1}^inftydfrac{x}{4^n(n!)^2}+ln314sumlimits_{n=1}^inftysumlimits_{k=1}^ndfrac{((k-1)!)^2sin xcos^{2k-1}x}{4^{n-k+1}(n!)^2(2k-1)!}+ln314sumlimits_{n=0}^inftysumlimits_{k=0}^ndfrac{(-1)^kn!sin^{2k+1}x}{(2n+1)!k!(n-k)!(2k+1)}+C$
$=ln314sumlimits_{n=0}^inftydfrac{x}{4^n(n!)^2}+ln314sumlimits_{n=1}^inftysumlimits_{k=1}^ndfrac{((k-1)!)^2sin xcos^{2k-1}x}{4^{n-k+1}(n!)^2(2k-1)!}+ln314sumlimits_{n=0}^inftysumlimits_{k=0}^ndfrac{(-1)^kn!sin^{2k+1}x}{(2n+1)!k!(n-k)!(2k+1)}+C$
$endgroup$
add a comment |
$begingroup$
$int314^{cos x}~dx$
$=int e^{cos x}ln314~dx$
$=ln314intsumlimits_{n=0}^inftydfrac{cos^{2n}x}{(2n)!}dx+ln314intsumlimits_{n=0}^inftydfrac{cos^{2n+1}x}{(2n+1)!}dx$
$=ln314intleft(1+sumlimits_{n=1}^inftydfrac{cos^{2n}x}{(2n)!}right)dx+ln314intsumlimits_{n=0}^inftydfrac{cos^{2n+1}x}{(2n+1)!}dx$
For $n$ is any natural number,
$intcos^{2n}x~dx=dfrac{(2n)!x}{4^n(n!)^2}+sumlimits_{k=1}^ndfrac{(2n)!((k-1)!)^2sin xcos^{2k-1}x}{4^{n-k+1}(n!)^2(2k-1)!}+C$
This result can be done by successive integration by parts.
For $n$ is any non-negative integer,
$intcos^{2n+1}x~dx$
$=intcos^{2n}x~d(sin x)$
$=int(1-sin^2x)^n~d(sin x)$
$=intsumlimits_{k=0}^nC_k^n(-1)^ksin^{2k}x~d(sin x)$
$=sumlimits_{k=0}^ndfrac{(-1)^kn!sin^{2k+1}x}{k!(n-k)!(2k+1)}+C$
$thereforeln314intleft(1+sumlimits_{n=1}^inftydfrac{cos^{2n}x}{(2n)!}right)dx+ln314intsumlimits_{n=0}^inftydfrac{cos^{2n+1}x}{(2n+1)!}dx$
$=xln314+ln314sumlimits_{n=1}^inftydfrac{x}{4^n(n!)^2}+ln314sumlimits_{n=1}^inftysumlimits_{k=1}^ndfrac{((k-1)!)^2sin xcos^{2k-1}x}{4^{n-k+1}(n!)^2(2k-1)!}+ln314sumlimits_{n=0}^inftysumlimits_{k=0}^ndfrac{(-1)^kn!sin^{2k+1}x}{(2n+1)!k!(n-k)!(2k+1)}+C$
$=ln314sumlimits_{n=0}^inftydfrac{x}{4^n(n!)^2}+ln314sumlimits_{n=1}^inftysumlimits_{k=1}^ndfrac{((k-1)!)^2sin xcos^{2k-1}x}{4^{n-k+1}(n!)^2(2k-1)!}+ln314sumlimits_{n=0}^inftysumlimits_{k=0}^ndfrac{(-1)^kn!sin^{2k+1}x}{(2n+1)!k!(n-k)!(2k+1)}+C$
$endgroup$
$int314^{cos x}~dx$
$=int e^{cos x}ln314~dx$
$=ln314intsumlimits_{n=0}^inftydfrac{cos^{2n}x}{(2n)!}dx+ln314intsumlimits_{n=0}^inftydfrac{cos^{2n+1}x}{(2n+1)!}dx$
$=ln314intleft(1+sumlimits_{n=1}^inftydfrac{cos^{2n}x}{(2n)!}right)dx+ln314intsumlimits_{n=0}^inftydfrac{cos^{2n+1}x}{(2n+1)!}dx$
For $n$ is any natural number,
$intcos^{2n}x~dx=dfrac{(2n)!x}{4^n(n!)^2}+sumlimits_{k=1}^ndfrac{(2n)!((k-1)!)^2sin xcos^{2k-1}x}{4^{n-k+1}(n!)^2(2k-1)!}+C$
This result can be done by successive integration by parts.
For $n$ is any non-negative integer,
$intcos^{2n+1}x~dx$
$=intcos^{2n}x~d(sin x)$
$=int(1-sin^2x)^n~d(sin x)$
$=intsumlimits_{k=0}^nC_k^n(-1)^ksin^{2k}x~d(sin x)$
$=sumlimits_{k=0}^ndfrac{(-1)^kn!sin^{2k+1}x}{k!(n-k)!(2k+1)}+C$
$thereforeln314intleft(1+sumlimits_{n=1}^inftydfrac{cos^{2n}x}{(2n)!}right)dx+ln314intsumlimits_{n=0}^inftydfrac{cos^{2n+1}x}{(2n+1)!}dx$
$=xln314+ln314sumlimits_{n=1}^inftydfrac{x}{4^n(n!)^2}+ln314sumlimits_{n=1}^inftysumlimits_{k=1}^ndfrac{((k-1)!)^2sin xcos^{2k-1}x}{4^{n-k+1}(n!)^2(2k-1)!}+ln314sumlimits_{n=0}^inftysumlimits_{k=0}^ndfrac{(-1)^kn!sin^{2k+1}x}{(2n+1)!k!(n-k)!(2k+1)}+C$
$=ln314sumlimits_{n=0}^inftydfrac{x}{4^n(n!)^2}+ln314sumlimits_{n=1}^inftysumlimits_{k=1}^ndfrac{((k-1)!)^2sin xcos^{2k-1}x}{4^{n-k+1}(n!)^2(2k-1)!}+ln314sumlimits_{n=0}^inftysumlimits_{k=0}^ndfrac{(-1)^kn!sin^{2k+1}x}{(2n+1)!k!(n-k)!(2k+1)}+C$
answered Dec 28 '18 at 12:29
Harry PeterHarry Peter
5,46911439
5,46911439
add a comment |
add a comment |
$begingroup$
The whole point of substitution by parts is to substitute.
You are trying to find
$int 314^{cos x} sin x dx$.
If you substitute $u = cos x$ then $314^{cos x}$ becomes $314^u$.
And $du = -sin x dx$ so $sin x dx$.
So $int 314^{cos x} sin x dx = int -314^{u}du$.
And as $sin a^x dx = frac {a^x}{ln a} + C$
We have $int 314^{cos x} sin x dx = int -314^{u}du= -frac {314^u}{ln 314} = -frac {314^{cos x}}{ln 314}$
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2
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Why are you calling this substitution by parts? This is just substitution... The whole point of integration by parts is to undo the product rule.
$endgroup$
– JavaMan
Dec 10 '18 at 17:44
add a comment |
$begingroup$
The whole point of substitution by parts is to substitute.
You are trying to find
$int 314^{cos x} sin x dx$.
If you substitute $u = cos x$ then $314^{cos x}$ becomes $314^u$.
And $du = -sin x dx$ so $sin x dx$.
So $int 314^{cos x} sin x dx = int -314^{u}du$.
And as $sin a^x dx = frac {a^x}{ln a} + C$
We have $int 314^{cos x} sin x dx = int -314^{u}du= -frac {314^u}{ln 314} = -frac {314^{cos x}}{ln 314}$
$endgroup$
2
$begingroup$
Why are you calling this substitution by parts? This is just substitution... The whole point of integration by parts is to undo the product rule.
$endgroup$
– JavaMan
Dec 10 '18 at 17:44
add a comment |
$begingroup$
The whole point of substitution by parts is to substitute.
You are trying to find
$int 314^{cos x} sin x dx$.
If you substitute $u = cos x$ then $314^{cos x}$ becomes $314^u$.
And $du = -sin x dx$ so $sin x dx$.
So $int 314^{cos x} sin x dx = int -314^{u}du$.
And as $sin a^x dx = frac {a^x}{ln a} + C$
We have $int 314^{cos x} sin x dx = int -314^{u}du= -frac {314^u}{ln 314} = -frac {314^{cos x}}{ln 314}$
$endgroup$
The whole point of substitution by parts is to substitute.
You are trying to find
$int 314^{cos x} sin x dx$.
If you substitute $u = cos x$ then $314^{cos x}$ becomes $314^u$.
And $du = -sin x dx$ so $sin x dx$.
So $int 314^{cos x} sin x dx = int -314^{u}du$.
And as $sin a^x dx = frac {a^x}{ln a} + C$
We have $int 314^{cos x} sin x dx = int -314^{u}du= -frac {314^u}{ln 314} = -frac {314^{cos x}}{ln 314}$
answered Dec 10 '18 at 17:40
fleabloodfleablood
69.6k22685
69.6k22685
2
$begingroup$
Why are you calling this substitution by parts? This is just substitution... The whole point of integration by parts is to undo the product rule.
$endgroup$
– JavaMan
Dec 10 '18 at 17:44
add a comment |
2
$begingroup$
Why are you calling this substitution by parts? This is just substitution... The whole point of integration by parts is to undo the product rule.
$endgroup$
– JavaMan
Dec 10 '18 at 17:44
2
2
$begingroup$
Why are you calling this substitution by parts? This is just substitution... The whole point of integration by parts is to undo the product rule.
$endgroup$
– JavaMan
Dec 10 '18 at 17:44
$begingroup$
Why are you calling this substitution by parts? This is just substitution... The whole point of integration by parts is to undo the product rule.
$endgroup$
– JavaMan
Dec 10 '18 at 17:44
add a comment |
$begingroup$
By parts,
$$int 314^{cos x}sin x,dx=-314^{cos x}cos x-log314int 314^{cos x}sin^2x,dx$$
leads you about nowhere.
$endgroup$
add a comment |
$begingroup$
By parts,
$$int 314^{cos x}sin x,dx=-314^{cos x}cos x-log314int 314^{cos x}sin^2x,dx$$
leads you about nowhere.
$endgroup$
add a comment |
$begingroup$
By parts,
$$int 314^{cos x}sin x,dx=-314^{cos x}cos x-log314int 314^{cos x}sin^2x,dx$$
leads you about nowhere.
$endgroup$
By parts,
$$int 314^{cos x}sin x,dx=-314^{cos x}cos x-log314int 314^{cos x}sin^2x,dx$$
leads you about nowhere.
answered Dec 10 '18 at 17:41
Yves DaoustYves Daoust
126k672225
126k672225
add a comment |
add a comment |
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$begingroup$
This is not an integral to do by parts.
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– T. Bongers
Dec 10 '18 at 17:22
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Your by-parts integration is wrong.
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– Yves Daoust
Dec 10 '18 at 17:31
$begingroup$
The integrals $int a^{cos x} dx$ do not have solutions in terms of elementary functions in general, but the original integral in the image does using the substitution $u = cos x$ as indicated by the answer below.
$endgroup$
– JavaMan
Dec 10 '18 at 17:33
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Please use mathjax to format your equations next time so we don't have to do it for you
$endgroup$
– Jam
Dec 10 '18 at 17:51
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The "art" of integration by parts is to substitute $u$ for something buried deeply within something and to balance that with $dv$ being something easy and expandible on the surface. You choice that $u = sin x $ and $dv = 314^{cos x}dx$ is the exact opposite if that. Try $dv= sin x$ so $v =-cos x$ and $u=314{-v}$ and $int 314^{cos x} dx = int u dv = int 314^{-v} dv$. (ALthough switching the negatives so $v=cos x$ and $int - 314^{v}dv$ will be easier.
$endgroup$
– fleablood
Dec 10 '18 at 17:53