Bài 4:
a) 5.(2x - 1) - 4.(8 - 3x) =7
10x -5 -32+12x = 7
22x-37 = 7
22x = 44
x = 2
b) 3x.(x - 2) - x.(1 + 3x) =14
3x² - 6x -x- 3x² = 14
-7x = 14
x = -2
c) 7.(2x - 5) - 5.(7x - 2) + 2.(5x - 7) = (x - 2) - (x + 4)
14x -35 -35x +10 +10x-14 = x-2-x-4
14x-35x+10x -x+x = 35-10+14-2-4
-11x = 33
x = -3
d) 2x.(x + 3) - 3.(x^2 + 1) = x+1 - x.(x-2)
2x² + 6x - 3x²-3 = x+1 -x² +2x
2x²-3x²+x²+6x-x-2x = 3+1
3x = 4
x = 4/3
e) 5.(3x + 5) - 4.(2x - 3) = 5x+3.(2x + 12) +1
15x +25 -8x+12 = 5x +6x+36+1
15x-8x-5x-6x = -25-12+36+1
-4x = 0
x = 0
f) 2.(5x - 8) - 3.(4x - 5) = 4.(3x - 4) +11
10x -16 -12x+15 = 12x-16+11
10x-12x-12x = 16-15-16+11
-14x = -4
x = 2/7
g) (x + 8)(x + 6) - x^2 = 104
x² +6x+8x+48-x² = 104
14x = 56
x = 4