Question

Phân tích đa thức thành nhân tử x(x+1) (x+2) (x+3) +1

Answer 1

\(=\left(x^2+3x\right)\left(x^2+3x+2\right)+1\\ =\left(x^2+3x\right)^2+2\left(x^2+3x\right)+1\\ =\left(x^2+3x+1\right)^2\)

Answer 2

\(=\left[x\left(x+3\right)\right]\left[\left(x+1\right)\left(x+2\right)\right]+1=\left(x^2+3x\right)\left(x^2+3x+1\right)+1\)

Đặt \(x^2+3x=t\)

\(\left(x^2+3x\right)\left(x^2+3x+2\right)+1=t\left(t+2\right)+1=t^2+2t+1=\left(t+1\right)^2=\left(x^2+3x+1\right)^2\)