Question

Phân tích đa thức thành nhân tử
a. x³-4x
b. x²-2xy-9+y²

Answer 1

\(c\text{â}ua:x^3-4x=x\left(x^2-4\right)=x\left(x^2-2^2\right)=x\left(x-2\right)\left(x+2\right)\)

\(c\text{â}ub:x^2-2xy-9+y^2=\left(x^2-2xy+y^2\right)-9=\left(x-y\right)^2-3^2=\left(x-y+3\right)\left(x+y-3\right)\)

Answer 2

a) ta có : \(x^3-4x=x\left(x^2-4\right)=x\left(x-2\right)\left(x+2\right)\)

b) ta có : \(x^2-2xy-9+y^2=x^2-2xy+y^2-9=\left(x-y\right)^2-9\)

\(=\left(x-y-3\right)\left(x-y+3\right)\)

Answer 3

a) x(x² - 4)

b) (x-y)² - 3² = (x-y+3)(x-y-3)