# Voltage and Electric field

wiiman3893
Here is the problem:

Given that electric potential is given as a function of x and y: V(x,y)=20x4 + 60y3

What is Ex at (2,1)?

I have tried using E=-DV/DV, but I keep getting confused on how to derive this as it's been a while since I took calculus. I am also unsure of how to plug in the number, like if I only derive the x component and only plug the x into it, or if the y component is involved.

Antiphon

wiiman3893
And how would I do that?

Antiphon
What's the formula for finding the gradient of a function in rectangular coordinates?