Решите систему уравнения: 4x-3y=-31 9x+5y=-11

{4x=3y-31; 9x+5y=-11

{x = (3y-31) / 4; 9 ((3y-31) / 4) + 5y=-11

{x = (3y-31) / 4; (27y-279+20) / 4=-11

{x = (3y-31) / 4; (47y-279+44) / 4=0

{x = (3y-31) / 4; (47y-235) / 4=0 / 4

{x = (3y-31) / 4; 47y-235=0

{x = (3y-31) / 4; 47y=235

{x = (3y-31) / 4; y=5

{x = (3*5-31) / 4; y=5

{x=-4; y=5

4 х=3 у-31

3 у-31

х = 4

9 (3 у-31) + 5 у = - 11

4

9 (3 у-31) + 20 у=-44

27 у-279+20 у=-44

47 у=-44+279

47 у=235

у=5

3*5-31 15-31 - 16

х = 4 = 4 = 4 = - 4

ответ: х=-4

у=5