Giải thích các bước giải:
a) 4x – (- 18) = 42
=> 4x + 18 = 42
=> 4x = 42 – 18
=> 4x = 24
=> x = 24 : 4
=> x = 6
b) - 21 – 2(x – 5) = - 37
=> - 2(x – 5) = (-37) + 21
=> -2(x - 5) = -16
=> (x – 5) = (-16) : (-2)
=> x – 5 = 8
=> x = 8 + 5
=> x = 13
c) - 5x + 4 = - 2x + (- 10)
=> -5x + 2x = (-10) – 4
=> (-5 + 2)x = -14
=> -3x = -14
=> x = 14/3
d) |2x - 1| + (-25) = - 16
=> |2x - 1| = (-16) + 25
=> |2x - 1| = 9
=> 2x – 1= 9
2x – 1= -9
TH1: 2x – 1= 9
2x = 9 + 1
2x = 10
x = 10 : 2
x = 5
TH2: 2x – 1= -9
2x = (-9) + 1
2x = -8
x = (-8) : 2
x = -4
e) -102 + (x + 6)^2 = -38
=>-102 + x^2 + 12x + 36 = -38
=>x^2 + 12x - 66 = -38
=>x^2 + 12x - 28 = 0
=>x^2 + 14x - 2x - 28 = 0
=>x(x + 14 ) - 2(x + 14) = 0
=>(x + 14) . (x - 2) =0
=> x = -14 hoặc x = 2
