计算 (2x+y-z+5)*(2x-y+z+5)

问题描述:

计算 (2x+y-z+5)*(2x-y+z+5)

=【(2x+5)+(y-z)】*【(2x+5)-(y-z)】
=(2x+5)^2-(y-z)^2
=4x^2+20x+25-y^2+2yz-z^2