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CEO
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If x is an integer, is 9^x + 9^-x = b? (1)3^x + 3^-x = [#permalink]
22 Sep 2003, 15:34
Question Stats:
0% (00:00) correct
100% (00:24) wrong based on 0 sessions
If x is an integer, is 9^x + 9^-x = b?
(1)3^x + 3^-x = square root of b+2
(2) x>0
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Intern
Joined: 03 May 2003
Posts: 30
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If x is an integer, is 9^x + 9^-x = b?
(1)3^x + 3^-x = square root of b+2
(2) x>0
(1)
(3)^x + 1/(3^x) = sqrb+2
square both sides and you get
9^x + 2 + 1/(9^x) = b + 2
subtract 2
and
9^x + 9^-x = b
so 1 is sufficient
(2) in suffient by itself
Therefore A is the answer
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