Calculus Math Help

Question

Given f(x, y) = x⁴ - 5xy⁵ - 4y³, find the following numerical values:

f_x(2, 2)

f_y(2, 2)

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I was able to find for f_y(2, 2) which is -848 and my online homework is telling me it's correct. The only thing that I'm having an issue with is f_x(2, 2). I got an answer of -120, but my online homework tells me it isn't correct. Thank you for the help :)

Answer 1

f(x, y) = x⁴ - 5xy⁵ - 4y³

f_x(x,y)=4x³-5y⁵

at (2,2)

f_x=32(1-5)=-128

Answer 2

f_x = 4x³ - 5y⁵ f_x(2,2) = 4(8) - 5(32) = -128

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