Question

Phân tích đa thức thành nhân tử:

5x(x-1)-x-1

Answer 1

`5x(x-1)-x-1`

`=5x^2-5x-x-1`

`=5x^2-6x-1`

`=5(x^2-6/5x-1/5)`

`=5[(x^2-6/5x+9/25)-9/25-1/5]`

`=5[(x-3/5)^2-14/15]`

`=5[(x-3/5)^2-(\sqrt{14}/5)^2]`

`=5(x-3/5-\sqrt{14}/5)(x-3/5+\sqrt{14}/5)`

Answer 2

5x(x-1)-x-1

\(=5x^2-5x-x-1\)

\(=5x^2-6x-1\)

\(=5\left(x^2-\frac65x-\frac15\right)\)

\(=5\left(x^2-2\cdot x\cdot\frac35+\frac{9}{25}-\frac{14}{25}\right)\)

\(=5\left\lbrack\left(x-\frac35\right)^2-\frac{14}{25}\right\rbrack=5\left(x-\frac35-\frac{\sqrt{14}}{5}\right)\left(x-\frac35+\frac{\sqrt{14}}{5}\right)\)