We multiply the first row by 4:

Now adding the two rows, we obtain:

Substituting + √2 into the first equation gives us

y = ± √2.

Likewise, substituting -√2 into the first equation also gives us

y = ± √2.

This gives us the solutions

(√2, √2), (√2, -√2), (-√2, √2) and (-√2, -√2).