Chain rule partial derivative

wololo

New member
Joined
Nov 3, 2015
Messages
1
(1 pt) Suppose that χ(s,t)=4s22t2,y\displaystyle \,\chi(s,\, t)\, =\, -4s^2\, -\, 2t^2,\,y\, a function of (s,t)\displaystyle \,(s,\, t)\, with y(1,1)=1\displaystyle \, y(1,\, 1)\, =\, 1\, and yt(1,1)=2.\displaystyle \, \dfrac{\partial y}{\partial t}\, (1,\, 1)\, =\, -2.

Suppose that u=xy,v\displaystyle \, u\, =\, xy,\, v\, a function of x,y\displaystyle \, x,\, y\, with vy(6,1)=4.\displaystyle \, \dfrac{\partial v}{\partial y}\, (-6,\, 1)\, =\,4.

Now suppose that f(s,t)=u(x(s,t),y(s,t))\displaystyle \, f(s,\,t)\, =\, u(x(s,\, t),\, y(s,\, t))\, and g(s,t)=v(x(s,t),y(s,t)).\displaystyle \, g(s,\, t)\, =\, v(x(s,\, t),\, y(s,\, t)).\, You are given:

. . . . .fs(1,1)=32,\displaystyle \dfrac{\partial f}{\partial s}\, (1,\, 1)\, =\, -32,\, . . .ft(1,1)=8,\displaystyle \dfrac{\partial f}{\partial t}\, (1,\, 1)\, =\, 8,\,. . .gs(1,1)=16.\displaystyle \dfrac{\partial g}{\partial s}\, (1,\, 1)\, =\, -16.

The value of gt(1,1)\displaystyle \, \dfrac{\partial g}{\partial t}\, (1,\, 1)\, must be:



dv/dt=dv/dx*dx/dt+dv/dy*dy/dt
dx/dt=-4t -> evaluate at (1,1) =-4
dv/dt=-4dv/dx+4(-2)
dv/dt=-4dv/dx-8

How can I find the missing dv/dx in order to get a value for dv/dt? Thanks!
 
Last edited by a moderator:
Top