I surely don't have any clue on how to that type of math sorry.
I don’t know I’m doin this so they can answer my question
<span>The first step you need to do is to rewrite
x+y=3
as y=3-x
</span><span>Now we can replace the y in the equation with our newfound value for y, which is
y=3-x.
So lets write it now like this
Q=x^2+2(3-y)^2
=x^2+18-12x+2x^2
=3x^2+18-12x
</span>Hope this helps
