Is it possible to show
As part of a larger proof I need the following to be true in order to make it work,
$(a+1){bchoose a+1}x^{a+1}(1-x)^{b-a-1}=a{bchoose a}x^a(1-x)^{b-a}$
Can anyone give me a hand?
binomial-coefficients
add a comment |
As part of a larger proof I need the following to be true in order to make it work,
$(a+1){bchoose a+1}x^{a+1}(1-x)^{b-a-1}=a{bchoose a}x^a(1-x)^{b-a}$
Can anyone give me a hand?
binomial-coefficients
add a comment |
As part of a larger proof I need the following to be true in order to make it work,
$(a+1){bchoose a+1}x^{a+1}(1-x)^{b-a-1}=a{bchoose a}x^a(1-x)^{b-a}$
Can anyone give me a hand?
binomial-coefficients
As part of a larger proof I need the following to be true in order to make it work,
$(a+1){bchoose a+1}x^{a+1}(1-x)^{b-a-1}=a{bchoose a}x^a(1-x)^{b-a}$
Can anyone give me a hand?
binomial-coefficients
binomial-coefficients
asked Nov 28 at 17:13
I suck at Maths
178
178
add a comment |
add a comment |
2 Answers
2
active
oldest
votes
It’s just really a sequence of simplifications.
$$(a+1){bchoose a+1}x^{a+1}(1-x)^{b-a-1}=a{bchoose a}x^a(1-x)^{b-a}$$
$$color{blue}{(a+1)}frac{b!}{color{blue}{(a+1)!}(b-(a+1))!}x^{a+1}(1-x)^{b-a-1}=color{green}{a}frac{b!}{color{green}{a!}(b-a)!}x^a(1-x)^{b-a}$$
$$frac{b!}{a!(b-a-1)!}color{blue}{x^{a+1}}color{green}{(1-x)^{b-a-1}}=frac{b!}{(a-1)!(b-a)!}color{blue}{x^a}color{green}{(1-x)^{b-a}}$$
$$frac{color{blue}{b!}}{color{green}{a!}color{purple}{(b-a-1)!}}x=frac{color{blue}{b!}}{color{green}{(a-1)!}color{purple}{(b-a)!}}(1-x)$$
$$frac{x}{a}=frac{1-x}{b-a} implies x(b-a)=a(1-x) implies bx-ax=a-ax implies bx = a$$
add a comment |
Unless $x=0$ or $x=1$, $$frac{(a+1)b!}{(a+1)!(b-a-1)!}x^{a+1}(1-x)^{b-a-1}=frac{ab!}{a!(b-a)!}x^a(1-x)^{b-a}$$
simplifies to
$$(b-a)x=a(1-x).$$
It also further simplifies to bx = a.
– Ofya
Nov 28 at 17:25
Since we know b > a, we can say that 1>x>0 as well
– Ofya
Nov 28 at 17:25
Actually, in the context of the problem earlier I showed that $a=bx$, so this solves my problem, thank you!
– I suck at Maths
Nov 28 at 17:36
add a comment |
Your Answer
StackExchange.ifUsing("editor", function () {
return StackExchange.using("mathjaxEditing", function () {
StackExchange.MarkdownEditor.creationCallbacks.add(function (editor, postfix) {
StackExchange.mathjaxEditing.prepareWmdForMathJax(editor, postfix, [["$", "$"], ["\\(","\\)"]]);
});
});
}, "mathjax-editing");
StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "69"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);
StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});
function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
noCode: true, onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});
}
});
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3017407%2fis-it-possible-to-show%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
It’s just really a sequence of simplifications.
$$(a+1){bchoose a+1}x^{a+1}(1-x)^{b-a-1}=a{bchoose a}x^a(1-x)^{b-a}$$
$$color{blue}{(a+1)}frac{b!}{color{blue}{(a+1)!}(b-(a+1))!}x^{a+1}(1-x)^{b-a-1}=color{green}{a}frac{b!}{color{green}{a!}(b-a)!}x^a(1-x)^{b-a}$$
$$frac{b!}{a!(b-a-1)!}color{blue}{x^{a+1}}color{green}{(1-x)^{b-a-1}}=frac{b!}{(a-1)!(b-a)!}color{blue}{x^a}color{green}{(1-x)^{b-a}}$$
$$frac{color{blue}{b!}}{color{green}{a!}color{purple}{(b-a-1)!}}x=frac{color{blue}{b!}}{color{green}{(a-1)!}color{purple}{(b-a)!}}(1-x)$$
$$frac{x}{a}=frac{1-x}{b-a} implies x(b-a)=a(1-x) implies bx-ax=a-ax implies bx = a$$
add a comment |
It’s just really a sequence of simplifications.
$$(a+1){bchoose a+1}x^{a+1}(1-x)^{b-a-1}=a{bchoose a}x^a(1-x)^{b-a}$$
$$color{blue}{(a+1)}frac{b!}{color{blue}{(a+1)!}(b-(a+1))!}x^{a+1}(1-x)^{b-a-1}=color{green}{a}frac{b!}{color{green}{a!}(b-a)!}x^a(1-x)^{b-a}$$
$$frac{b!}{a!(b-a-1)!}color{blue}{x^{a+1}}color{green}{(1-x)^{b-a-1}}=frac{b!}{(a-1)!(b-a)!}color{blue}{x^a}color{green}{(1-x)^{b-a}}$$
$$frac{color{blue}{b!}}{color{green}{a!}color{purple}{(b-a-1)!}}x=frac{color{blue}{b!}}{color{green}{(a-1)!}color{purple}{(b-a)!}}(1-x)$$
$$frac{x}{a}=frac{1-x}{b-a} implies x(b-a)=a(1-x) implies bx-ax=a-ax implies bx = a$$
add a comment |
It’s just really a sequence of simplifications.
$$(a+1){bchoose a+1}x^{a+1}(1-x)^{b-a-1}=a{bchoose a}x^a(1-x)^{b-a}$$
$$color{blue}{(a+1)}frac{b!}{color{blue}{(a+1)!}(b-(a+1))!}x^{a+1}(1-x)^{b-a-1}=color{green}{a}frac{b!}{color{green}{a!}(b-a)!}x^a(1-x)^{b-a}$$
$$frac{b!}{a!(b-a-1)!}color{blue}{x^{a+1}}color{green}{(1-x)^{b-a-1}}=frac{b!}{(a-1)!(b-a)!}color{blue}{x^a}color{green}{(1-x)^{b-a}}$$
$$frac{color{blue}{b!}}{color{green}{a!}color{purple}{(b-a-1)!}}x=frac{color{blue}{b!}}{color{green}{(a-1)!}color{purple}{(b-a)!}}(1-x)$$
$$frac{x}{a}=frac{1-x}{b-a} implies x(b-a)=a(1-x) implies bx-ax=a-ax implies bx = a$$
It’s just really a sequence of simplifications.
$$(a+1){bchoose a+1}x^{a+1}(1-x)^{b-a-1}=a{bchoose a}x^a(1-x)^{b-a}$$
$$color{blue}{(a+1)}frac{b!}{color{blue}{(a+1)!}(b-(a+1))!}x^{a+1}(1-x)^{b-a-1}=color{green}{a}frac{b!}{color{green}{a!}(b-a)!}x^a(1-x)^{b-a}$$
$$frac{b!}{a!(b-a-1)!}color{blue}{x^{a+1}}color{green}{(1-x)^{b-a-1}}=frac{b!}{(a-1)!(b-a)!}color{blue}{x^a}color{green}{(1-x)^{b-a}}$$
$$frac{color{blue}{b!}}{color{green}{a!}color{purple}{(b-a-1)!}}x=frac{color{blue}{b!}}{color{green}{(a-1)!}color{purple}{(b-a)!}}(1-x)$$
$$frac{x}{a}=frac{1-x}{b-a} implies x(b-a)=a(1-x) implies bx-ax=a-ax implies bx = a$$
answered Nov 28 at 17:42
KM101
3,988417
3,988417
add a comment |
add a comment |
Unless $x=0$ or $x=1$, $$frac{(a+1)b!}{(a+1)!(b-a-1)!}x^{a+1}(1-x)^{b-a-1}=frac{ab!}{a!(b-a)!}x^a(1-x)^{b-a}$$
simplifies to
$$(b-a)x=a(1-x).$$
It also further simplifies to bx = a.
– Ofya
Nov 28 at 17:25
Since we know b > a, we can say that 1>x>0 as well
– Ofya
Nov 28 at 17:25
Actually, in the context of the problem earlier I showed that $a=bx$, so this solves my problem, thank you!
– I suck at Maths
Nov 28 at 17:36
add a comment |
Unless $x=0$ or $x=1$, $$frac{(a+1)b!}{(a+1)!(b-a-1)!}x^{a+1}(1-x)^{b-a-1}=frac{ab!}{a!(b-a)!}x^a(1-x)^{b-a}$$
simplifies to
$$(b-a)x=a(1-x).$$
It also further simplifies to bx = a.
– Ofya
Nov 28 at 17:25
Since we know b > a, we can say that 1>x>0 as well
– Ofya
Nov 28 at 17:25
Actually, in the context of the problem earlier I showed that $a=bx$, so this solves my problem, thank you!
– I suck at Maths
Nov 28 at 17:36
add a comment |
Unless $x=0$ or $x=1$, $$frac{(a+1)b!}{(a+1)!(b-a-1)!}x^{a+1}(1-x)^{b-a-1}=frac{ab!}{a!(b-a)!}x^a(1-x)^{b-a}$$
simplifies to
$$(b-a)x=a(1-x).$$
Unless $x=0$ or $x=1$, $$frac{(a+1)b!}{(a+1)!(b-a-1)!}x^{a+1}(1-x)^{b-a-1}=frac{ab!}{a!(b-a)!}x^a(1-x)^{b-a}$$
simplifies to
$$(b-a)x=a(1-x).$$
answered Nov 28 at 17:24
Yves Daoust
124k671221
124k671221
It also further simplifies to bx = a.
– Ofya
Nov 28 at 17:25
Since we know b > a, we can say that 1>x>0 as well
– Ofya
Nov 28 at 17:25
Actually, in the context of the problem earlier I showed that $a=bx$, so this solves my problem, thank you!
– I suck at Maths
Nov 28 at 17:36
add a comment |
It also further simplifies to bx = a.
– Ofya
Nov 28 at 17:25
Since we know b > a, we can say that 1>x>0 as well
– Ofya
Nov 28 at 17:25
Actually, in the context of the problem earlier I showed that $a=bx$, so this solves my problem, thank you!
– I suck at Maths
Nov 28 at 17:36
It also further simplifies to bx = a.
– Ofya
Nov 28 at 17:25
It also further simplifies to bx = a.
– Ofya
Nov 28 at 17:25
Since we know b > a, we can say that 1>x>0 as well
– Ofya
Nov 28 at 17:25
Since we know b > a, we can say that 1>x>0 as well
– Ofya
Nov 28 at 17:25
Actually, in the context of the problem earlier I showed that $a=bx$, so this solves my problem, thank you!
– I suck at Maths
Nov 28 at 17:36
Actually, in the context of the problem earlier I showed that $a=bx$, so this solves my problem, thank you!
– I suck at Maths
Nov 28 at 17:36
add a comment |
Thanks for contributing an answer to Mathematics Stack Exchange!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
Use MathJax to format equations. MathJax reference.
To learn more, see our tips on writing great answers.
Some of your past answers have not been well-received, and you're in danger of being blocked from answering.
Please pay close attention to the following guidance:
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
To learn more, see our tips on writing great answers.
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3017407%2fis-it-possible-to-show%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown