已知函数f(x)=xex求f(x)的单调区间与极值
问题描述：
已知函数f(x)=xex求f(x)的单调区间与极值
答
f'(x) = (1+x)e^x
f'(x)=0 x= -1
lim{x to +∞}xe^x = +∞
lim{x to -∞}xe^x = lim{y to -∞}((-y) / e^y) = 0