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If 1/2^m + [#permalink]
Expert's post 00:00

Question Stats: 100% (00:40) correct 0% (00:00) wrong based on 13 sessions
If $$\frac{1}{2^m} + \frac{1}{2^m} = \frac{1}{2^x}$$, then x expressed in terms of m is

A. $$\frac{m}{2}$$

B. $$m - 1$$

C. $$m + 1$$

D. $$2m$$

E. $$m^2$$

Kudos to the right answer and explanation
[Reveal] Spoiler: OA

_________________ Manager  Joined: 15 Jan 2018
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Re: If 1/2^m + [#permalink]
1
KUDOS
To get rid of all the fractions, multiply all terms by 2^m and by 2^x to get:

2^x +2^x = 2^m

Collect similar terms:

2x2^x = 2^m

Collect same bases on the left by thinking of the 2 as 2^1:

2^1x2^x = 2^m

Multiplying the same bases with different exponents cant be done by adding the exponents:

2^(1+x) = 2^m

Now we can ignore the bases:

1+x = m

Subtract 1:

x = m - 1

The answer is B.
_________________

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Need help with GRE math? Check out our ground-breaking books and app. Re: If 1/2^m +   [#permalink] 07 Mar 2018, 19:28
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