alleryStart learning →If a + b = 7 and a^2 + b^2 = 29, then ab equals what?
A12
B8
C10
D11
Answer & Solution
Correct answer: C. 10
2ab = (a+b)^2 - (a^2+b^2) = 49 - 29 = 20, so ab = 10.
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