Question

Найдите решение системы уравнений способом подстановки
2x+3(x+y)=11
{
7(x+3y)-6x=-59

Answer 1

{2х+3х+3у=11
{7х+21у–6х=–59
{5х+3у=11
{х+21у=–59
{х=–59–21у
{5(–59–21у)+3у=11
–295–105у+3у=11
–102у=306
у=–3
х=–59–21•(–3)=4
Ответ: (4; –3)

Answer 2

2x+3(x+y)=11
7(x+3y)-6y=-59
********
2x+3x+3y=11
7x+21y-6x=-59
********
5x+3y=11
x+21=-59
********
5x+3y=11
x=-59-21y
********
5(59-2y)+3y=11
-295-105Y=3y=11
-295-102y=11
-102y=11+295
-102y=306
y=306:102
y=3
******
2x=3(x+3)=11
2x+3x+9=11
5x=11-9
5x=2
x=2:5
x=0.4
ответ:y=3;x=0,4