(x-y+z)2+(z-y)2+2(x-y+z)(y-z)
=(x-y+z)2+2(x-y+z)(y-z)+(y-z)2
= (x-y+z+y-z)2=x2
\(\left(x-y+z\right)^2+\left(z-y\right)^2+2\left(x-y+z\right)\left(y-z\right)\)
\(=\left(x-y+z\right)^2+\left(y-z\right)^2+2\left(x-y+z\right)\left(y-z\right)\)
\(=\left(x-y+z+y-z\right)^2\)
\(=x^2\)