Answer
$f_x=2xy$, $f_y=x^2-12y^3$.
Work Step by Step
$f(x,y)=x^2y-3y^4$
To find $f_x$ we treat y as a constant and differentiate with respect to $x$.
$f_x=2xy$
To find $f_y$ we treat x as a constant and differentiate with respect to $y$.
$f_y=x^2-12y^3$
