Answer: Choice A
U = (x+3)
V = 7
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Explanation:
If we let U = (x+3), then the original expression turns into U^2 + 14U + 49
This factors to (U+7)^2 when using the perfect square factor rule which in general is (a+b)^2 = a^2+2ab+b^2
Comparing the last term 49 with b^2, we see that b^2 = 49 leads to b = 7
So that must mean V = 7 in order to have
(U+V)^2 = U^2+2UV+V^2 = U^2 + 14U + 49
be a true statement
