Question

Phân tích đa thức thành nhân tử:

a) 5x² – 10x

b) x² – y² – 2x + 2y

c) 4x² – 4xy – 8y²

Answer 1

Answer 2

a) \(5x^2-10x=5x\left(x-2\right)\)

b) \(x^2-y^2-2x+2y\\ =\left(x^2-y^2\right)-\left(2x-2y\right)\\ =\left(x-y\right)\left(x+y\right)-2\left(x-y\right)\\ =\left(x-y\right)\left(x+y-2\right)\)

c) \(4x^2-4xy-8y^2\\ =\left(4x^2-4xy+y^2\right)-9y^2\\ =\left(2x-y\right)^2-\left(3y\right)^2\\ =\left(2x-y-3y\right)\left(2x-y+3y\right)\\ =\left(2x-4y\right)\left(2x+2y\right)\\ =2\left(x-2y\right)2\left(x+y\right)\\ =4\left(x-2y\right)\left(x+y\right)\)