2) 5/8+5/6=5*4+5*3/24=35/24=1(11/24)
1) 5/8-5/6=5*4+5*3/24 =5/24
3) 5/24:(-15/16)=-(5/24*16/15)=2/9
4) 35/24:7/8=35/24*8/7=5/3=1(2/3)
5)2/9-5/3=30/9=10/3=3(1/3)
3х - 2(3х-1) = 2х + 7
3х - 6х + 2 = 2х + 7
2х + 6х - 3х = 2 - 7
5х = -5
х = -5 : 5
х = -1
Проверка.
1) 3х = 3 • (-1) = -3
2) 2(3х-1) =2• [3(-1) -1] = 2 • (-4) = -8
3) 2х +7 = 2(-1) +7 = -2 + 7 = 5
4) -3 - (-8) = - 3+ 8 = 5
5=5
25-3.6*1.5+2.5=25-5.4+2.5=22.1
(25-3.6) (1.5+2,5)=21.4*4=85,6
25-3.6(1.5+2.5)=25-14.4=10.6
Примем неизвестное число за х, составим и решим уравнение
х:4-2=7
х=36