How do you solve $x+y= -1$ and $x-y=3$ ?

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Answer 1 · 2015-08-03T18:10:09

$color(red)( x=1,y=-2)$

One way is to use the method of elimination.

Step 1. Enter the equations.

[1] $x+y=-1$
[2] $x-y=3$

Step 2. Add Equations 1 and 2.

$2x=2$

[3] $x=1$

Step 3. Substitute Equation 3 in Equation 2.

$x+y=-1$
$1+y=-1$

$y=-2$

Solution: $x=1,y=-2$

Check: Substitute the values of $x$ and $y$ in Equation 1.

$x+y=-1$
$1+(-2)=-1$
$1-2=-1$
$-1=-1$

It checks!

Our solution is correct.

How do you solve x+y= -1x+y= -1 and x-y=3x-y=3?