Question

Решите системы уравнений
2у=-х+13
х+у=11
__________

Способом подстановки
у-х=-3
2х+у=9
________

2с-у=2
3с-2у=3

Answer 1

1) x=11-y
2y= -(11-y)+13

x=11-y
2y= -11+y+13

x=11-y
y=2

y=2
x=9

Answer 2

2) y=x-3; 2x+x-3=9; 3x=12; x=4; y=1

Answer 3

3) y=2c-2; 3c-2*(2c-2)=3; 3c-4c+4=3; c=1; y= 0