\(x\left(y-z\right)-z\left(y-x\right)\)
\(=xy-xz-zy+zx\)
\(=xy-zy=y\left(x-z\right)\)
\(\left(x+y\right)\left(x-y\right)\)
\(=x^2-xy+xy-y^2=x^2-y^2\)
\(\left(x+y\right)^2-\left(x-y\right)^2\)
\(=\left(x+y-x+y\right)\left(x+y+x-y\right)\)
\(=2y+2x=2\left(x+y\right)\)
a, x(y-z)-z(y-x)=xy-xz-zy+xz
=xy-zy=y(x-z)
b,(x+y)(x-y)=x2-y2
c,(x+y)2-(x-y)2=(x+y+x-y)(x+y-x+y)
=2x.2y
=4xy
a) x.(y-z)-z.(y-x) = (xy-xz)-(zy-zx)=xy-xz-zy+zx=xy-zy=y.(x-z)
b)(x+y).(x-y)=(x^2-xy)+(yx-y^2)=x^2-xy+yx-y^2=x^2-y^2
c)(x+y)^2 - (x-y)^2 = (x+y).(x+y) - (x-y).(x-y)=[(x^2+xy)+(yx+y^2)] - [(x^2-xy)-(yx-y^2]=(x^2+xy+yx+y^2)-(x^2-xy-yx+y^2)
=x^2+xy+yx+y^2-x^2+xy+yx-y^2=xy+yx+xy+yx = 4xy
k mình nha!