(x+3y-2z)^2
问题描述：
(x+3y-2z)^2
答
=(x+3y-2z)*(x+3y-2z)
=x*x+3xy-2xz+3xy+9y*y-6yz-2xz-6yz+4z*z
=x*x+6xy-4xz-12yz+9y*y+4z*z
或
=[(x+3y)-2z]^2
=(x+3y)^2-4z(x+3y)+4z^2
=x^2+6xy+9y^2-4xz-12yz+4z^2
答
【（(x+3y）-2z】^2