1.(x+y-z)*(x-y+z) 2.(x+y+z)*(x-y+z)要完整的过程
问题描述：
1.(x+y-z)*(x-y+z) 2.(x+y+z)*(x-y+z)要完整的过程
答
这是一条公式:得X平方-Y平方-Z平方
答
说的复杂点好了1.(x+y-z)*(x-y+z) 2.(x+y+z)*(x-y+z)
=x^2-xy+xz+xy-y^2+yz-zx+zy-z^2 =x^2-xy+xz+xy-y^2+yz+xz-zy+z^2
=x^2-y^2-z^2+2yz =x^2-y^2+z^2+2xz
答
1.(x+y-z)*(x-y+z) =[x+(y-z)][x-(y-z)]=x²-(y-z)²=x²-y²-z²+2yz2.(x+y+z)*(x-y+z)=[(x+z)+y][(x+z)-y]=(x+z)²-y²=x²+z²+2xz-y²
答
=x2-（y-z）2
=（x+z）2-y2
分开的平方差公式