Đáp án:
(6–3x)(2x+4)=0
1) 6 - 3x = 0 ⇔ -3x = -6 ⇔ x = 2
2) 2x + 4 = 0 ⇔ 2x = -4 ⇔ x = -2
25–4x²=0
⇔ (5 - 2x)(5 + 2x) = 0
1) 5 - 2x = 0 ⇔ -2x = -5 ⇔ x = 5/2
2) 5 + 2x = 0 ⇔ 2x = -5 ⇔ x = -5/2
x²+4x+4=0
⇔ (x + 2)² = 0
⇔ x + 2 = 0
⇔ x = -2
x² - 3x + 2=0
⇔ x² - x - 2x + 2 = 0
⇔ x(x - 1) - 2(x - 1) = 0
⇔ (x - 1)(x - 2) = 0
1) x - 1 = 0 ⇔ x = 1
2) x - 2 = 0 ⇔ x = 2
