x-2x+3x-4x+5x.+99x-100x=25求解
问题描述:
x-2x+3x-4x+5x.+99x-100x=25求解
答
x(1-2+3-4+...+99-100)=25
x[(1-2)+(3-4)+...+(99-100)]=25
x(-1×50)=25
x=25/(-50)=-1/2