Answer:
Using the relationship (x -y)^2 = x^2 + y^2 - 2xy
We can assume that we have:
2a^2 = x^2
This means that x= √2a
we also can assume tbat Y = √2b
then we would have something like:
(√2a - √2*a)^2 = 2a^2 + 2b^2 - 4ab
Where i see that in the written question there is a 5ab instead of a 4ab, but i guess this may be a typo