Whats the best way of solving this ratio problem?












0












$begingroup$


I have a question relating to a school report that I submitted, essentially I was asked to prove why a certain value ($x_1$) had a large increase (40%) as compared with a second value ($x_2$). I wanted to prove it using the ratio of a second variable $y$.



Lets say the function is,
$$
x = y + C
$$

where $y$ is a variable and $C$ is a constant.



e.g. lets say there are two cars, and their speed ($x$) is described as a function of car engine size ($y$) and a drag coefficient ($C$), such that: $x = y + C$. I want to describe that the ratio of change in $x$ of car1 and car2, i.e. $x_2/x_1$ is equal to the ratio of the cars engine sizes $y_2/y_1$ added to a constant.



How do i express that the ratio of $x$ is equal to the ratio of $y + C$. I was thinking about writing it as:
$$
frac{x_2}{x_1} = frac{y_2 + C}{y_1 + C}
$$



or possibly;
$$
Delta x = frac{y_2 + C}{y_1 + C}
$$

Furthermore, I wondered if there's a simple way to relate $Delta x$ and $Delta y$ such that;
$$
Delta x = k Delta y
$$

I went and did some research on some of my old math, and realized that:
$$
Delta x = x_2 - x_1
$$




So whats the best way to express ratios using algebra?











share|cite|improve this question











$endgroup$








  • 1




    $begingroup$
    $Delta x = x_2-x_1 = (y_2+C)-(y_1+C) = y_2-y_1 = Delta y$. However, I would call this the change in speed, not ratio of speeds. Ratio of speed would simply be the first expression you wrote. Also, assuming $y_2>y_1$, and $C$ positive, $x_2/x_1$ would always be less than $y_2/y_1$. I dont think anything more can be said about this generally
    $endgroup$
    – Anvit
    Dec 5 '18 at 8:06


















0












$begingroup$


I have a question relating to a school report that I submitted, essentially I was asked to prove why a certain value ($x_1$) had a large increase (40%) as compared with a second value ($x_2$). I wanted to prove it using the ratio of a second variable $y$.



Lets say the function is,
$$
x = y + C
$$

where $y$ is a variable and $C$ is a constant.



e.g. lets say there are two cars, and their speed ($x$) is described as a function of car engine size ($y$) and a drag coefficient ($C$), such that: $x = y + C$. I want to describe that the ratio of change in $x$ of car1 and car2, i.e. $x_2/x_1$ is equal to the ratio of the cars engine sizes $y_2/y_1$ added to a constant.



How do i express that the ratio of $x$ is equal to the ratio of $y + C$. I was thinking about writing it as:
$$
frac{x_2}{x_1} = frac{y_2 + C}{y_1 + C}
$$



or possibly;
$$
Delta x = frac{y_2 + C}{y_1 + C}
$$

Furthermore, I wondered if there's a simple way to relate $Delta x$ and $Delta y$ such that;
$$
Delta x = k Delta y
$$

I went and did some research on some of my old math, and realized that:
$$
Delta x = x_2 - x_1
$$




So whats the best way to express ratios using algebra?











share|cite|improve this question











$endgroup$








  • 1




    $begingroup$
    $Delta x = x_2-x_1 = (y_2+C)-(y_1+C) = y_2-y_1 = Delta y$. However, I would call this the change in speed, not ratio of speeds. Ratio of speed would simply be the first expression you wrote. Also, assuming $y_2>y_1$, and $C$ positive, $x_2/x_1$ would always be less than $y_2/y_1$. I dont think anything more can be said about this generally
    $endgroup$
    – Anvit
    Dec 5 '18 at 8:06
















0












0








0





$begingroup$


I have a question relating to a school report that I submitted, essentially I was asked to prove why a certain value ($x_1$) had a large increase (40%) as compared with a second value ($x_2$). I wanted to prove it using the ratio of a second variable $y$.



Lets say the function is,
$$
x = y + C
$$

where $y$ is a variable and $C$ is a constant.



e.g. lets say there are two cars, and their speed ($x$) is described as a function of car engine size ($y$) and a drag coefficient ($C$), such that: $x = y + C$. I want to describe that the ratio of change in $x$ of car1 and car2, i.e. $x_2/x_1$ is equal to the ratio of the cars engine sizes $y_2/y_1$ added to a constant.



How do i express that the ratio of $x$ is equal to the ratio of $y + C$. I was thinking about writing it as:
$$
frac{x_2}{x_1} = frac{y_2 + C}{y_1 + C}
$$



or possibly;
$$
Delta x = frac{y_2 + C}{y_1 + C}
$$

Furthermore, I wondered if there's a simple way to relate $Delta x$ and $Delta y$ such that;
$$
Delta x = k Delta y
$$

I went and did some research on some of my old math, and realized that:
$$
Delta x = x_2 - x_1
$$




So whats the best way to express ratios using algebra?











share|cite|improve this question











$endgroup$




I have a question relating to a school report that I submitted, essentially I was asked to prove why a certain value ($x_1$) had a large increase (40%) as compared with a second value ($x_2$). I wanted to prove it using the ratio of a second variable $y$.



Lets say the function is,
$$
x = y + C
$$

where $y$ is a variable and $C$ is a constant.



e.g. lets say there are two cars, and their speed ($x$) is described as a function of car engine size ($y$) and a drag coefficient ($C$), such that: $x = y + C$. I want to describe that the ratio of change in $x$ of car1 and car2, i.e. $x_2/x_1$ is equal to the ratio of the cars engine sizes $y_2/y_1$ added to a constant.



How do i express that the ratio of $x$ is equal to the ratio of $y + C$. I was thinking about writing it as:
$$
frac{x_2}{x_1} = frac{y_2 + C}{y_1 + C}
$$



or possibly;
$$
Delta x = frac{y_2 + C}{y_1 + C}
$$

Furthermore, I wondered if there's a simple way to relate $Delta x$ and $Delta y$ such that;
$$
Delta x = k Delta y
$$

I went and did some research on some of my old math, and realized that:
$$
Delta x = x_2 - x_1
$$




So whats the best way to express ratios using algebra?








ratio






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Dec 5 '18 at 7:59









Daniele Tampieri

1,8891619




1,8891619










asked Dec 5 '18 at 7:48









AfroeskimoAfroeskimo

114




114








  • 1




    $begingroup$
    $Delta x = x_2-x_1 = (y_2+C)-(y_1+C) = y_2-y_1 = Delta y$. However, I would call this the change in speed, not ratio of speeds. Ratio of speed would simply be the first expression you wrote. Also, assuming $y_2>y_1$, and $C$ positive, $x_2/x_1$ would always be less than $y_2/y_1$. I dont think anything more can be said about this generally
    $endgroup$
    – Anvit
    Dec 5 '18 at 8:06
















  • 1




    $begingroup$
    $Delta x = x_2-x_1 = (y_2+C)-(y_1+C) = y_2-y_1 = Delta y$. However, I would call this the change in speed, not ratio of speeds. Ratio of speed would simply be the first expression you wrote. Also, assuming $y_2>y_1$, and $C$ positive, $x_2/x_1$ would always be less than $y_2/y_1$. I dont think anything more can be said about this generally
    $endgroup$
    – Anvit
    Dec 5 '18 at 8:06










1




1




$begingroup$
$Delta x = x_2-x_1 = (y_2+C)-(y_1+C) = y_2-y_1 = Delta y$. However, I would call this the change in speed, not ratio of speeds. Ratio of speed would simply be the first expression you wrote. Also, assuming $y_2>y_1$, and $C$ positive, $x_2/x_1$ would always be less than $y_2/y_1$. I dont think anything more can be said about this generally
$endgroup$
– Anvit
Dec 5 '18 at 8:06






$begingroup$
$Delta x = x_2-x_1 = (y_2+C)-(y_1+C) = y_2-y_1 = Delta y$. However, I would call this the change in speed, not ratio of speeds. Ratio of speed would simply be the first expression you wrote. Also, assuming $y_2>y_1$, and $C$ positive, $x_2/x_1$ would always be less than $y_2/y_1$. I dont think anything more can be said about this generally
$endgroup$
– Anvit
Dec 5 '18 at 8:06












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