2) 2a + (a + 2b) - (b - 3a) = 2a + a + 2b - b + 3a = 6a + b
б) 3x - 2(x + 1) + 6(5 - 2x) = 3x - 2x - 1 + 30 - 12x = -11x + 29
в) -3(4 - x) - (7 + 3x) = -12 + 3x - 7 - 3x = -19
3) 2(x + 6) - (3 - 5x) = 0
2x + 12 - 3 + 5x =0
7x + 9 = 0
7x = -9
x = -9/7 = -1 целая 2/7
б) 2(x + 6)(3 - 5x) = 0
2(3x + 18 - 5x² - 30x) = 0
6x + 36 - 10x² - 60x = 0
-10x² - 54x + 36 = 0
10x² + 54x - 36 = 0
5x² + 27x - 18 = 0
D = b² - 4ac = 729 - 4*5*(-18) = 1089 = 33²
x1 = (-27 + 33)/10 = 6/10 = 3/5
x2 = (-27 - 33)/10 = -60/10 = -6
в) 5 - (2x + 4) = 2 + x
5 - 2x - 4 = 2 + x
-2x - x = 2 - 5 + 4
-3x = 1
х = - 1/3
г) 3x - 2(x + 1) = 2 + (5 - x)
3x - 2x - 2 = 2 + 5 - x
x - 2 = 7 - x
x + x = 7 + 2
2x = 9
x = 9/2 = 4 целых 1/2
д) (6x + 8)*2 = 16 + 12x
12x + 16 = 16 + 12x
0 = 0
ответ: бесконечное множество корней. (любые числа)
е) 5x + 4 = 2x - 3,7
5x - 3x = -3,7 - 4
2x = -7,7
x = - 7,7/2 = - 3,85