Let $R(s,t) = G(u(s,t), v(s,t))$, where $G$, $u$, and $v$ are differentiable. What is $R_s(1,2)$ and...
$begingroup$
Here's everything that's given:
$u(1,2)$ = $5$
$u_s(1,2)$ = $4$
$u_t(1,2)$ = $-3$
$v(1,2)$ = $7$
$v_s(1,2)$ = $2$
$v_t(1,2)$ = $6$
$G_u(5,7)$ = $9$
$G_v(5,7)$ = $-2$
I would post my attempt, but I have no idea where to start. I know I have to split $R_s$ and $R_t$ into a bunch of partial derivatives involving the other variables, but I haven't found anything that works, nor do I have an answer in my book to check for an answer.
multivariable-calculus derivatives partial-derivative chain-rule
$endgroup$
add a comment |
$begingroup$
Here's everything that's given:
$u(1,2)$ = $5$
$u_s(1,2)$ = $4$
$u_t(1,2)$ = $-3$
$v(1,2)$ = $7$
$v_s(1,2)$ = $2$
$v_t(1,2)$ = $6$
$G_u(5,7)$ = $9$
$G_v(5,7)$ = $-2$
I would post my attempt, but I have no idea where to start. I know I have to split $R_s$ and $R_t$ into a bunch of partial derivatives involving the other variables, but I haven't found anything that works, nor do I have an answer in my book to check for an answer.
multivariable-calculus derivatives partial-derivative chain-rule
$endgroup$
add a comment |
$begingroup$
Here's everything that's given:
$u(1,2)$ = $5$
$u_s(1,2)$ = $4$
$u_t(1,2)$ = $-3$
$v(1,2)$ = $7$
$v_s(1,2)$ = $2$
$v_t(1,2)$ = $6$
$G_u(5,7)$ = $9$
$G_v(5,7)$ = $-2$
I would post my attempt, but I have no idea where to start. I know I have to split $R_s$ and $R_t$ into a bunch of partial derivatives involving the other variables, but I haven't found anything that works, nor do I have an answer in my book to check for an answer.
multivariable-calculus derivatives partial-derivative chain-rule
$endgroup$
Here's everything that's given:
$u(1,2)$ = $5$
$u_s(1,2)$ = $4$
$u_t(1,2)$ = $-3$
$v(1,2)$ = $7$
$v_s(1,2)$ = $2$
$v_t(1,2)$ = $6$
$G_u(5,7)$ = $9$
$G_v(5,7)$ = $-2$
I would post my attempt, but I have no idea where to start. I know I have to split $R_s$ and $R_t$ into a bunch of partial derivatives involving the other variables, but I haven't found anything that works, nor do I have an answer in my book to check for an answer.
multivariable-calculus derivatives partial-derivative chain-rule
multivariable-calculus derivatives partial-derivative chain-rule
edited Nov 10 '15 at 21:28
JVV
9981419
9981419
asked Nov 9 '15 at 7:12
ChrisChris
3691215
3691215
add a comment |
add a comment |
1 Answer
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$begingroup$
Since $G$ is a function of $u$ and $v$, and $u$ and $v$ are each functions of $s$ and $t$, we have: $$R_s=frac{partial G}{partial u}cdotfrac{partial u}{partial s} + frac{partial G}{partial v}cdotfrac{partial v}{partial s}, quad R_t=frac{partial G}{partial u}cdotfrac{partial u}{partial t} + frac{partial G}{partial v}cdotfrac{partial v}{partial t}.$$
Now, at the point with coordinates $s=1,t=2$, we obtain: $$R_s(1,2)=G_u(5,7)cdot u_s(1,2)+ G_v(5,7)cdot v_s(1,2)=9cdot4-2cdot2=32.$$
$$R_t(1,2)=G_u(5,7)cdot u_t(1,2)+ G_v(5,7)cdot v_t(1,2)=9cdot(-3)-2cdot6=-39.$$
$endgroup$
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1 Answer
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1 Answer
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$begingroup$
Since $G$ is a function of $u$ and $v$, and $u$ and $v$ are each functions of $s$ and $t$, we have: $$R_s=frac{partial G}{partial u}cdotfrac{partial u}{partial s} + frac{partial G}{partial v}cdotfrac{partial v}{partial s}, quad R_t=frac{partial G}{partial u}cdotfrac{partial u}{partial t} + frac{partial G}{partial v}cdotfrac{partial v}{partial t}.$$
Now, at the point with coordinates $s=1,t=2$, we obtain: $$R_s(1,2)=G_u(5,7)cdot u_s(1,2)+ G_v(5,7)cdot v_s(1,2)=9cdot4-2cdot2=32.$$
$$R_t(1,2)=G_u(5,7)cdot u_t(1,2)+ G_v(5,7)cdot v_t(1,2)=9cdot(-3)-2cdot6=-39.$$
$endgroup$
add a comment |
$begingroup$
Since $G$ is a function of $u$ and $v$, and $u$ and $v$ are each functions of $s$ and $t$, we have: $$R_s=frac{partial G}{partial u}cdotfrac{partial u}{partial s} + frac{partial G}{partial v}cdotfrac{partial v}{partial s}, quad R_t=frac{partial G}{partial u}cdotfrac{partial u}{partial t} + frac{partial G}{partial v}cdotfrac{partial v}{partial t}.$$
Now, at the point with coordinates $s=1,t=2$, we obtain: $$R_s(1,2)=G_u(5,7)cdot u_s(1,2)+ G_v(5,7)cdot v_s(1,2)=9cdot4-2cdot2=32.$$
$$R_t(1,2)=G_u(5,7)cdot u_t(1,2)+ G_v(5,7)cdot v_t(1,2)=9cdot(-3)-2cdot6=-39.$$
$endgroup$
add a comment |
$begingroup$
Since $G$ is a function of $u$ and $v$, and $u$ and $v$ are each functions of $s$ and $t$, we have: $$R_s=frac{partial G}{partial u}cdotfrac{partial u}{partial s} + frac{partial G}{partial v}cdotfrac{partial v}{partial s}, quad R_t=frac{partial G}{partial u}cdotfrac{partial u}{partial t} + frac{partial G}{partial v}cdotfrac{partial v}{partial t}.$$
Now, at the point with coordinates $s=1,t=2$, we obtain: $$R_s(1,2)=G_u(5,7)cdot u_s(1,2)+ G_v(5,7)cdot v_s(1,2)=9cdot4-2cdot2=32.$$
$$R_t(1,2)=G_u(5,7)cdot u_t(1,2)+ G_v(5,7)cdot v_t(1,2)=9cdot(-3)-2cdot6=-39.$$
$endgroup$
Since $G$ is a function of $u$ and $v$, and $u$ and $v$ are each functions of $s$ and $t$, we have: $$R_s=frac{partial G}{partial u}cdotfrac{partial u}{partial s} + frac{partial G}{partial v}cdotfrac{partial v}{partial s}, quad R_t=frac{partial G}{partial u}cdotfrac{partial u}{partial t} + frac{partial G}{partial v}cdotfrac{partial v}{partial t}.$$
Now, at the point with coordinates $s=1,t=2$, we obtain: $$R_s(1,2)=G_u(5,7)cdot u_s(1,2)+ G_v(5,7)cdot v_s(1,2)=9cdot4-2cdot2=32.$$
$$R_t(1,2)=G_u(5,7)cdot u_t(1,2)+ G_v(5,7)cdot v_t(1,2)=9cdot(-3)-2cdot6=-39.$$
answered Nov 10 '15 at 21:25
JVVJVV
9981419
9981419
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