Bài 1:
a) 5x (x - 2000) - x + 2000 = 0
⇔ 5x (x - 2000) - (x - 2000) = 0
⇔ (x - 2000)( 5x - 1) = 0
⇔ x - 2000 = 0 hay 5x - 1 = 0
⇔ x = 2000 hay 5x = 1
⇔ x = 2000 hay x = $\frac{1}{5}$
b) 2x(x - 2) + 3(x - 2) = 0
⇔ (x - 2)(2x + 3) = 0
⇔ x - 2 = 0 hay 2x + 3 = 0
⇔ x = 2 hay 2x = -3
⇔ x = 2 hay x = -$\frac{3}{2}$
Bài 2:
a) 7x + 7y
⇔ 7(x + y)
b) 2x²y - 6xy²
⇔ 2xy(x - 3y)
c) 3x(x - 1) + 7x²(x - 1)
⇔ (x - 1)(3x + 7x²)
e) x² - 6xy + 9y²
⇔ x² - 2.x.3y + (3y)²
⇔ (x - 3y)²
g) x³ - 64
⇔ x³ - 4³
⇔ (x - 4)(x² + 4x + 16)
