Given f(x,y)=−5x2+5xy3−2y4\displaystyle {f{{\left({x},{y}\right)}}}=-{5}{x}^{{2}}+{5}{x}{y}^{{3}}-{2}{y}^{{4}}, find the following numerical values:

fx(4,4)\displaystyle {{f}_{{x}}{\left({4},{4}\right)}} =

fy(4,4)\displaystyle {{f}_{{y}}{\left({4},{4}\right)}} =

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