Question

Answer 1

Bài 2

a) 2x³ + 6x² - 4x

= 2x(x² + 3x - 2)

b) (2x + 5)² - 9x²

= (2x + 5 - 3x)(2x + 5 + 3x)

= (5 - 3x)(5x + 5)

= 5(5 - 3x)(x + 1)

c) 4x² - 9y² + 4x - 6y

= (4x² - 9y²) + (4x - 6y)

= (2x - 3y)(2x + 3y) + 2(2x - 3y)

= (2x - 3y)(2x + 3y + 2)

Answer 2

Bài 3:

a) ĐKXĐ: \(x\ne\pm6;x\ne0;x\ne3\)  

b) \(A=\left(\dfrac{x}{x^2-36}+\dfrac{6-x}{6x+x^2}\right):\dfrac{2x-6}{x^2+6x}+\dfrac{x}{6-x}\)

\(A=\left[\dfrac{x}{\left(x+6\right)\left(x-6\right)}+\dfrac{6-x}{x\left(x+6\right)}\right]:\dfrac{2\left(x-3\right)}{x\left(x+6\right)}+\dfrac{x}{6-x}\)

\(A=\left[\dfrac{x^2}{x\left(x+6\right)\left(x-6\right)}+\dfrac{\left(6-x\right)\left(x-6\right)}{x\left(x+6\right)\left(x-6\right)}\right]\cdot\dfrac{x\left(x+6\right)}{2\left(x-3\right)}+\dfrac{x}{6-x}\)

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

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

\(A=\dfrac{36}{x\left(x+6\right)\left(x-6\right)}\cdot\dfrac{x\left(x+6\right)}{2\left(x-3\right)}+\dfrac{x}{6-x}\)

\(A=\dfrac{36}{\left(x-6\right)\cdot2\left(x-3\right)}+\dfrac{x}{6-x}\)

\(A=\dfrac{18}{\left(x-6\right)\left(x-3\right)}-\dfrac{x\left(x-3\right)}{\left(x-6\right)\left(x-3\right)}\)

\(A=\dfrac{18-x^2+3x}{\left(x-3\right)\left(x-6\right)}\)

\(A=\dfrac{-\left(x-6\right)\left(x+3\right)}{\left(x-3\right)\left(x-6\right)}\)

\(A=-\dfrac{x+3}{x-3}\)