1) 12а - 3b
a = - 3/4
b = 5/6
12 • (-3/4) - 3 • (5/6) = -9 - 5/2 = -9 - 2.5 = -11.5
2) 1 - 0.6x
1 + 0.6 x
x = 5
1 - 0.6 • 5 = 1 - 3 = -2
1 + 0.6 • 5 = 1 + 3 = 4
1 - 0.6 x < 1 + 0.6x
3) a) 12a - 10b - 10a + 6b = 12a - 10a - 10b + 6b = 2a - 4b = 2(a - 2b)
б) 4(3х - 2) + 7 = 12х - 8 + 7 = 12х - 1
в) 8х - (2х + 5) + (х - 1) = 8х - 2х - 5 + х - 1 = 7х - 6
4) -5(0.6с - 1.2) - 1.5с - 3, при с = -4/9
-5(6/10 • (-4/9) - 6/5) - 3/2 • (-4/9) - 3 = -5(3/5 • (-4/9) - 6/5) + 12/18 - 3 = -5(-12/45 - 6/5) + 2/3 - 3 = -5(-4/15 - 6/5) + 2/3 - 9/3 = -5(-4/15 - 18/5) - 7/3 = -5(-22/5) - 7/3 = 22 - 7/3 = 66/3 - 7/3 = 59/3.