Find the Indicated Partial Derivative $f ( x , y ) = x ^ { 2 } y ^ { 4 } - 3 x ^ { 4 } y ; f _ { m x }$

Multiple Choice

Find the indicated partial derivative. $f ( x , y ) = x ^ { 2 } y ^ { 4 } - 3 x ^ { 4 } y ; f _ { m x }$

A) $f _ { m x } = 12 x ^ { 2 } y$
B) $f _ { m x } = - 36 x y$
C) $f _ { m x } = 3 x y$
D) $f _ { m x } = - 72 x y$
E) $f _ { m x } = - 3 x y$