Question

Solve the equation system and make a proof x+y=−1
3x+y=3
​

Answer 1

x+y=1

3x+y=3

per substitution :

x=1-y

we replace x

3x+y=3

3(1-y)+y=3

3-3y+y=3

-2y=0

y= 0

x+y=1

x+0=1

x=1

solution [1;0}

we check

3x+y=3

3*1+0=3

x+y=1

1+0=1