把式子展开成幂级数
x^2 e^(x^2)= sum(1/n! * x^(2n+5)
在x=0处,幂级数的n次导数值是x^n的系数乘以n!
所以f^(99)(0) = 99!/47!
f^(100)(0) = 0, 因为没有x^100项
f(x)=x^5*e^(x^2)
=x^5*∑(n=0->∞) (x^2)^n/n!
=∑(n=0->∞) x^(2n+5)/n!
f'(x)=∑(n=0->∞) x^(2n+4)*(2n+5)/n!
f''(x)=∑(n=0->∞) x^(2n+3)*(2n+5)(2n+4)/n!
......
f^(99)(x)=∑(n=47->∞) x^(2n-94)*(2n+5)!/(2n-93)!n!
f^(100)(x)=∑(n=48->∞) x^(2n-95)*(2n+5)!/(2n-94)!n!
所以f^(99)(0)=(2*47+5)!/(2*47-93)!47!=99!/47!
f^(100)(0)=0
f(x)=x^5.e^(x^2)
f^(99)(0)=0
f^(100)(0)=0