Question

[Tsukino Usagi]

Phân tích đa thức thành nhân tử:

xy(x+y) + yz(y-z) - zx(z+x)

Answer 1

[Phương An]

\(xy\left(x+y\right)+yz\left(y-z\right)-xz\left(x+z\right)\)

\(=xy\left(x+y\right)+z\left[y\left(y-z\right)-x\left(x+z\right)\right]\)

\(=xy\left(x+y\right)+z\left(y^2-yz-x^2-xz\right)\)

\(=xy\left(x+y\right)+z\left[\left(y^2-x^2\right)-\left(yz+xz\right)\right]\)

\(=xy\left(x+y\right)+z\left[\left(y-x\right)\left(y+x\right)-z\left(x+y\right)\right]\)

\(=xy\left(x+y\right)+z\left(x+y\right)\left(y-z-x\right)\)

\(=\left(x+y\right)\left[xy+z\left(y-x-z\right)\right]\)

\(=\left(x+y\right)\left(xy-yz-xz-z^2\right)\)