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What is the value of x ? (1) 4^(x + 1) + 4^x = 320 (2) x^2 = 9 [#permalink]
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Value of x. We want 1 unique value.

(2) x = +3, or x = -3. NOT SUFFICIENT

(1) Actually we dont even have to solve it to know you can find out the value of x here.
Anyways if you insist, here is the solution

Take \(4^x\) common,

\(4^x(4+1) = 320\)
or, \(4^x=64 = 4^3\)
or, x=3
SUFFICIENT

Ans: A
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Re: What is the value of x ? (1)4^(x + 1) + 4^x = 320 (2)x^2 = 9 [#permalink]
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Re: What is the value of x ? (1)4^(x + 1) + 4^x = 320 (2)x^2 = 9 [#permalink]
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