（2x+y-z+10)(2x-y+z+10)
=[(2x+10)+(y-z)][(2x+10)-(y-z)]
=(2x+10)²-(y-z)²
=4x^2+40x+100-y^2+2yz-z^2
=4x^2-y^2-z^2+2yz+40x+100