题目内容：

y=3^-x*x^2,求导

优质解答

Iny = (-x)In3+2Inx
(Iny)‘= -In3+2/x
y' / y = -In3 + 2/x
y' = (-In3 + 2/x)y
y' = (-In3 + 2/x)[3^(-x)·(x²)]
= (-x²In3+2x)·3^(-x)