(x+7)(x+6)-(x-2)(x+1)=?

问题描述:

(x+7)(x+6)-(x-2)(x+1)=?

(x+7)(x+6)-(x-2)(x+1)
=x^2+13x+42-x^2+x+2
=14x+44
=2(7x+22)