Question

What should be added to (x² + 2xy + y^2)
to get (x² + 3y²)
?​

Answer 1

Answer:

see the attached document

Answer 2

Answer:

(x²+2xy+y²)-(x²+3y²)

x²+2xy+y²-x²-3y²

2xy-2y²

Your answer is 2xy-2y² or 2y(x-y)