Question

Phân tích đa thức sau thành nhân tử

x²y + 5xy - 14y

x³ - 5x² - 14x

Answer 1

Ta có:  x²y+5xy-14y

        = y(x²+5x-14)

        = y(x+7)(x-2)

           x³-5x²-14x

        = x(x²-5x-14)

        = x(x-7)(x+2)

Answer 2

\(x^2y+5xy-14y\)

\(=x^2y-2xy+7xy-14y\)

\(=xy\left(x-2\right)+7y\left(x-2\right)\)

\(=\left(x-2\right)\left(xy+7y\right)\)

\(x^3-5x^2-14x\)

\(=x^3-7x^2+2x^2-14x\)

\(=x^2\left(x-7\right)+2x\left(x-7\right)\)

\(=\left(x^2+2x\right)\left(x-7\right)\)

\(=x\left(x+2\right)\left(x-7\right)\)