Saturday, July 31, 2010
GMAT Question of the Day
19. If A2 + B2 = 15 and AB = 10, what is the value of the expression
(A – B)2 + (A + B)2 ?
(a) 10.
(b) 20.
(c) 30.
(d) 60.
(e) 70.
(A – B)2 + (A + B)2
=A2 – 2AB + B2 + A2 + 2AB + B2
=2(A2 + B2)
=30.
The best answer is C.
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