Question

Use addition to solve the linear system of equations. x-y=4 x+2y=4

Answer 1

Hey, There 20percntcooler! :)

To solve these equations, we will need to substitute.
$x-y=4$
or 
$4+y=x$

We can substitute this for x so, we don't have to deal with two different variables.
$x+2y=4$
or if substituted:
$4+y+2y=4$

Solve for y.
$4+y+2y=4$
Add like terms.
$4+3y=4$
Subtract 4 from both sides.
$(4+3y)-4=(4)-4$
$3y=0$
Divide both sides by 3.
$(3y)/3=(0)/3$
$y=0$

Now lets input the value for y into the equation to find the value of x.
$x-0=4$
Add 0 to both sides.
$(x-0)+0=(4)+0$
$x=4$

$x=4$
$y=0$

Hope this helps.
-Benjamin