Question

Решить систему уравнений:
x+y=2
3x+4y=5

Answer 1

х+у=2
3х+4у=5

х=2-у
3(2-у)+4у=5
6-3у+4у=5
-3у+4у=5-6
у=-1
х=2-(-1)=3
Ответ: х=3, у=-1

Answer 2

$left { {{x+y=2} atop {3x+4y=5}} right. \ \ left { {{y=2-x} atop {3x+4cdot(2-x)=5}} right. \ \ left { {{y=2-x} atop {3x+8-4x=5}} right. \ \ left { {{y=2-x} atop {3x-4x=5-8}} right. \ \ left { {{y=2-x} atop {-x=-3}} right. \ \ left { {{y=2-3} atop {x=3}} right. \ \ left { {{y=-1} atop {x=3}} right.$