Giải thích các bước giải:
a) 5 – (x – 6) = 4(3 – 2x)
<=> 5 - x + 6 = 12 - 8x
<=> 11 - x = 12 - 8x
<=> - x + 8x = 12 - 11
<=> 7x = 1
<=> x = 1/7
b) 2x(x + 2)2 – 8x2 = 2(x – 2)(x2 + 2x + 4)
<=> 4x^2 + 8x - 8x^2 = 2x^3 - 16
<=> - 4x^2 + 8x = 2x^3 - 16
<=> 2x^2 - 4x = - x^3 + 8
<=> 2x^2 - 4x + x^3 - 8 = 0
<=> 2x ( x - 2 ) + ( x - 2 ) . ( x^2 + 2x + 4 ) = 0
<=> ( x - 2 ) ( 2x + x^2 + 2x + 4 ) = 0
<=> ( x- 2 ) ( 4x + x^2 + 4 ) = 0
<=> ( x - 2 ) ( x^2 + 4x + 4 ) = 0
<=> ( x - 2 ) ( x +2 ) ^2 = 0
<=> x = cộng trừ 2
c) 7 – (2x + 4) = – (x + 4)
<=> 7 - 2x - 4 = -x - 4
<=> 3 - 2x = -x - 4
<=> -2x + x = -4 - 3
<=> -x = -7
<=> x = 7