Question

Phân tích đa thức sau thành nhân tử:

\(x^2-7x+12\)

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

\(4x^2-3x-1\)

Answer 1

Ta có : \(4x^2-3x-1\)

\(=4x^2-4x+x-1\)

\(=4x\left(x-1\right)+\left(x-1\right)\)

\(=\left(x-1\right)\left(4x+1\right)\)

Answer 2

Ta có : \(x^2-7x+12\)

\(=x^2-3x-4x+12\)

\(=x\left(x-3\right)-\left(4x-12\right)\)

\(=x\left(x-3\right)-4\left(x-3\right)\)

\(=\left(x-4\right)\left(x-3\right)\)

Answer 3

Ta có : \(x^2-5x-14\)

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

\(=x^2+2x-\left(7x+14\right)\)

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

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

Answer 4

\(x^2-7x+12\)

\(=x^2-3x-4x+12\)

\(=x\left(x-3\right)-4\left(x-3\right)\)

\(=\left(x-3\right)\left(x-4\right)\)

   

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

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

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

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

   

\(4x^2-3x-1\)

\(=4x^2-4x+x-1\)

\(=4x\left(x-1\right)+\left(x-1\right)\)

\(=\left(4x+1\right)\left(x-1\right)\)