Partial Derivative

[KEYWEST17]

Find the partial derivatives indicated. Assume the variables are restricted to a domain on which the function is defined.

f(x,y)= x^2+5x^4 y

Find fx(3,4)

Find fy(3,4)

 

[Idealistic]

when doing partial derivatives, you just derive according to the selected variable while holding all other(s) constant.

in your equation:

f(x,y)= x[sup:1o31cau9]2[/sup:1o31cau9] + (5x[sup:1o31cau9]4[/sup:1o31cau9])y (i'm assuming it's times y)

fx = 2x + (20x[sup:1o31cau9]3[/sup:1o31cau9])y

fx evaluated at (x,y) = (3,4) is

2(3) + 20(27)(4) = 2166