please solve

please solve

G eloisa

6sqrt(x) * 6sqrt(x)=36sqrt(x^2)

6sqrt(y)*-6sqrt(y)=-36sqrt

Then I reduced 36x-36y.

I’m not sure what I’m missing.

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The expression $(6\sqrt{x}+6\sqrt{y})(6\sqrt{x}-6\sqrt{y})$equals $Ax+By$
where A equals:

and B equals: