Question

How do you solve for y: `2x + y = 8` , `2x - y = 8`?

Answer 1

`y=0`

Explanation:

Notice that the `y` terms are additive inverses.
Add the two equations together to eliminate them.

`" "2x+y=8" "...A`
`" "2x-y = 8" "...B`

`A+B" "4x = 16`

`" "x = 4`

If `x =4, " "y=0`

We could have guessed that from looking at the equation.
In one the `y` is added and in the other `y` is subtracted, yet it does not affect the value of the equation at all. The only value of `y` that would allow this to happen would be `y=0`