Answer
$f_x=y^2$
$f_y=2xy$
$f_z=-4z$
Work Step by Step
Take the first partial derivatives of the given function. When taking a partial derivative with respect to x, treat y and z as constants, with respect to y, treat x and z as constants, and with respect to z, treat x and y as constants:
$f_x=y^2$
$f_y=2xy$
$f_z=-4z$