(x+2)^2+(2x+1)(2x-1)-4x(x+1)

问题描述:

(x+2)^2+(2x+1)(2x-1)-4x(x+1)

(x+2)^2+(2x+1)(2x-1)-4x(x+1) =x+2x+4+4x-1-4x-4x =x-2x+3 =(x-1)+2