Đáp án:
a) -2x – (x – 17) = 34 – (-x + 25)
⇔ -2x - x + 17 = 34 + x - 25
⇔ -2x - x - x = 34 - 25 - 17
⇔ -4x = -8
⇔ x = 2
b) 17x – ( -16x – 37) = 2x + 43
⇔ 17x + 16x + 37 = 2x + 43
⇔ 17x + 16x - 2x = 43 - 37
⇔ 31x = 6
⇔ x = 31/6
c) -2x –3. (x – 17) = 34 – 2(-x + 25)
⇔ -2x - 3x + 51 = 34 + 2x - 50
⇔ -2x -3x - 2x = 34 - 50 - 51
⇔ -7x = -67
⇔ x = 67/7
d) x.(x + 7) = 0
1) x = 0
2) x + 7 = 0 ⇔ x = -7
e) (x + 12).(x-3) = 0
1) x + 12 = 0 ⇔ x = -12
2) x - 3 = 0 ⇔ x = 3