Question

phân tich thành nhân tử

x^2-5x-2

3x^2-5x-14

15x^2+7x-12

Answer 1

Các đa thức trên đều không phân tích được thành nhân tử

Answer 2

a: \(=x^2-5x+\dfrac{25}{4}-\dfrac{33}{4}\)

\(=\left(x-\dfrac{5}{2}\right)^2-\dfrac{33}{4}\)

\(=\left(x-\dfrac{5}{2}-\dfrac{\sqrt{33}}{2}\right)\left(x-\dfrac{5}{2}+\dfrac{\sqrt{33}}{2}\right)\)

b: \(=3\left(x^2-\dfrac{5}{3}x-\dfrac{14}{3}\right)\)

\(=3\left(x^2-2\cdot x\cdot\dfrac{5}{6}+\dfrac{25}{36}-\dfrac{193}{36}\right)\)

\(=3\left[\left(x-\dfrac{5}{6}\right)^2-\dfrac{193}{36}\right]\)

\(=3\left(x-\dfrac{5}{6}-\dfrac{\sqrt{193}}{6}\right)\left(x-\dfrac{5}{6}+\dfrac{\sqrt{193}}{6}\right)\)

c: \(=15\left(x^2+\dfrac{7}{15}x-\dfrac{4}{5}\right)\)

\(=15\left(x^2+2\cdot x\cdot\dfrac{7}{30}+\dfrac{49}{900}-\dfrac{769}{900}\right)\)

\(=15\left(x+\dfrac{7}{30}-\dfrac{\sqrt{769}}{30}\right)\left(x+\dfrac{7}{30}+\dfrac{\sqrt{769}}{30}\right)\)