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Explanation:
I'm assuming you meant to say (a+y)^2 + 2y
Replace each copy of 'a' with 5. Replace each copy of 'y' with -3. Use PEMDAS to simplify.
(a+y)^2 + 2y
(5 + (-3))^2 + 2(-3)
(5-3)^2 + 2(-3)
(2)^2 + 2(-3)
4 + 2(-3)
4 - 6
-2
So (a+y)^2 + 2y = -2 when a = 5 and y = -3.