f(x)
=∫(1->x^2) (x^2-t)e^(-t^2) dt
=x^2.∫(1->x^2) e^(-t^2) dt -∫(1->x^2) t.e^(-t^2) dt
f'(x)
=2x∫(1->x^2) e^(-t^2) dt +2x^3.e^(-x^4) -2x^3.e^(-x^4)
=2x∫(1->x^2) e^(-t^2) dt
f'(x) = 0
x=0 or 1 or -1
f''(x) =2∫(1->x^2) e^(-t^2) dt +4x^2. e^(-x^4)
f''(0) = -2∫(0->1) e^(-t^2) dt <0 (max)
f''(1) = 4. e^(-1) >0 (min)
f''(-1) = 4. e^(-1) >0 (min)
单调递增区间
增加: [-1, 0] U [-1, ∞)
减小: (- ∞, -1] U [0 , 1]