Question

Answer 1

Câu 1: C

Câu 2: B

Câu 3: C

Cau 4: D

Câu 5: B

Câu 6: D

Câu 7: D

Câu 8: C

Câu 9: B

Câu 10: B

Câu 7:

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

b: \(x^2-9-2xy+y^2\)

\(=\left(x^2-2xy+y^2\right)-9\)

\(=\left(x-y\right)^2-9=\left(x-y-3\right)\left(x-y+3\right)\)

c: \(x^2+6x-7\)

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

=x(x+7)-(x+7)

=(x+7)(x-1)