(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Find the partial of z with respect to x keeping r constant.

2. Relevant equations

z=x^{2}+y^{2}

x= rcos(t)

y= rsin(t)

3. The attempt at a solution

= r^2(cos(t))^2 + r^2(sin(t))^2

use product rule on "x" and hold r and y constant

= [0(cos(t))^2 + r^2(2cos(t))(-sin(t)))] + 0

simplify terms

= -2r^2(cos(t)sin(t))

I am confused because to hold r constant, does that mean i hold both r and y constant?

thanks

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# Homework Help: Partial Differentiation of an expression.

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