РЕШИТЕ СИСТЕМУ УРАВНЕНИЙ СПОСОБОМ ПОДСТАНОВКИ:
1) {5х-2(у+4)=0
{6(2х+3)-у=41
2){6х+5у=6
{2х+у=-2
3){15+2(х+3у)=3(4х+у)
{2(5х-у)-3у=2+3(2х-у)
1) 5х - 2*(у+4) = 0
6*(2х+3)-у = 41
5х-2у-8 =0
12х+18-у = 41
5х-2у = 8
12х-у = 23 *(-1)
у = -23+12х
5х-2*(-23+12х) = 8
5х+46-24х = 8
-19х = 8-46
х = -38:(-19)
х = 2
у = 1
Проверяем:
5*2-2(1+4) = 10-10 = 0
6*(2*2+3)-1 = 42-1 =41
2) 6х+5у = 6
2х+у = -2
6х+5у = 6
у = -2-2х
6х+5*(-2-2х) = 6
6х-10-10х = 6
-4х = 16
х = -4
у = 6
6*(-4)+5*6 = -24+30 = 6
2*(-4)+6 = -8+6 = -2
3) 15+2(х+3у)=3(4х+у)
2(5х-у)-3у = 2+3(2х-у)
15+2х+6у = 12х+3у
10х-2у-3у = 2+6х-3у
-10х+3у = -15
4х-2у = 2 :(-2)
-2х+у = -1
у = 2х-1
-10х+3*(2х-1)= -15
-10х+6х-3 = -15
-4х-3 = -15
-4х = -12
х = -12:(-4)
х = 3
у = 5
15+2(3+3*5)= 3*(4*3+5)
15+36 = 3*17
51 = 51
2(5*3-5)-3*5 = 2+3*(2*3-5)
20-15 = 3+2
5 = 5