Решите уровнение и сделайте проверку а) 5(x-2)-4x=-13 б) 7х-0,9(10х+20)=4 в) 5+2(8-3х)-21=2

5(х-2)-4х=-13
5х-10-4х=-13
5х-4х=-13+10
х=-3

5(-3-2)-4*-3=-13

7х-0.9(10х+20)=4

7х-9х-18=4
7х-9х=4+18
-2х=22
х=22:-2
х=-11
7*-11-0.9(10*-11+20)=4

5+2(8-3х)-21=2
5+16-6х-21=2
-6х=2-5-16+21
-6х=2
х=2:-6
х=-0.333

1)5(x-2)-4x=-13, 5x-10-4x=-13, x=-13+10, x=-3
L(-3)=5(-3-2)-4.(-3)=5.(-5)+12=-25+12=-13
P(-3)=-13, L(-3)=P(-3)
2)7x-0,9(10x+20)=4, 7x-9x-18=4, -2x=4+18, -2x=22, x=-11
L(-11)=7.(-11)-0,9(-110+20)=-77-0,9.(-90)=-77+81=4
P(-11)=4, L(-11)=P(-11)
3)5+2(8-3x)-21=2, 5+16-6x-21=2,21-6x-21=2,-6x=2, x=-1/3
L(-1/3)=5+2(8+1)-21=5+2.9-21=5+18-21=23-21=2
P(-1/3)=2, L(-1/3)=P(-1/3)