(x+y+z)的二次方—(x-y-z)的二次方
问题描述:
(x+y+z)的二次方—(x-y-z)的二次方
答
平方差公式,x²-y²=(x+y)(x-y)
答
4xy+4xz
答
(x+y+z)^2-(x-y-z)^2
=(x+y+z+x-y-z)(x+y+z-x+y+z)
=2x(2y+2z)
=4x(y+z)
=4xy+4xz