f'(x)=[x'*(x+1)(x+2)(x+3)(x+4)+x(x+1)'*(x+2)(x+3)(x+4)+x(x+1)(x+2)'*(x+3)(x+4)+x(x+1)(x+2)(x+3)'*(x+4)+x(x+1)(x+2)(x+3)(x+4)']/24
=[(x+1)(x+2)(x+3)(x+4)+x(x+2)(x+3)(x+4)+x(x+1)(x+3)(x+4)+x(x+1)(x+2)(x+4)+x(x+1)(x+2)(x+3)]/24
后面每项都有x
则x=0时等于0
所以f'(0)=(0+1)(0+2)(0+3)(0+4)/24=1