Question

System of Equations y=-x-1 y+x=3 Solve?

Answer 1

Solve by substitution

$\sf{y=-x-1}$
$\sf{y+x=3}$

Just plug in y=-x-1 into y+x=3

So we get:

$\sf{(-x-1)+x=3}$

Simplify that:

$\sf{-1=3}$

And since that is not true, that means this system of equations has no solutions!