f(x)的导数为:2x+e的ax次幂+x^2*a*e的ax次幂=e^(ax)*x*(2+ax)
所以当a=0时,f(x)的减区间是(-无穷,0】,增区间(0,+无穷)
当a0,增区间(-无穷,-2/a】并【0,+无穷),减区间(-2/a,0)