当x=-1时,求x+2x²+3x³+……+99x^99+100x^100的值

问题描述:

当x=-1时,求x+2x²+3x³+……+99x^99+100x^100的值

x+2x²+3x³+……+99x^99+100x^100
=-1+2-3+4-5+6+.+(-99)+100
=(-1+2)+(-3+4)+(-5+6)+.+(-99+100)
=1+1+1+...+1
=1*50
=50