Quy đồng mẫu thức ba phân thức x/(x^2 - 2xy + y^2 - z^2); y/(y^2 - 2zy + z^2 -x^2)

* Hướng dẫn giải

$x^2-2xy+y^2-z^2={\left(x-y\right)}^2-z^2$ = (x – y + z)(x – y − z)

$y^2-2yz+z^2-x^2={\left(y-z\right)}^2-x^2$ = (y – z + x)(y – z − x) = -(x +y – z)(x – y + z)

$z^2-2zx+x^2-y^2={\left(z-x\right)}^2-y^2$ = (z – x + y)(z – x -y) = (x- y –z).(x + y – z)

MTC = (x – y + z)(x + y − z)(x – y − z)