It looks like you've completely misstated the equation. Is this even data sufficiency?Enginpasa1 wrote:a^2+B^2=2AB=9
how do you deduce down to (A+B)^2=9 I dont see this step
answer is 3 or -3.
Based on what you've posted, I'm going to try to reverse engineer the question. Wish me luck!
Q: what's the value of a+b?
(1) a^2 + b^2 + 2ab = 9
The left side of the equation is a classic quadratic - a perfect square (which is usually written as a^2 + 2ab + b^2). We can simplify the left side to:
(a+b) (a+b) or (a+b)^2
so, we have (a+b)^2 = 9
if we had x^2 = 9, we'd know that x = +3 or -3
(a+b)^2 is the same thing as x^2, so we know that (a+b) = +3 or -3
Since we get 2 values, statement (1) is insufficient.
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Was I close?
In the future, please post the entire question, it makes it much easier for people to help you out.
