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Senior Manager Joined: 20 May 2014
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If x = 10^-1, what is the value of (x + 1/x)(1/x)? [#permalink] 00:00

Question Stats: 100% (00:50) correct 0% (00:00) wrong based on 13 sessions
If $$x = 10^{-1}$$, what is the value of $$(x + \frac{1}{x})(\frac{1}{x})$$?

OA:
[Reveal] Spoiler:
101
Intern Joined: 18 Jun 2014
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Kudos [?]: 26 , given: 15

Re: If x = 10^-1, what is the value of (x + 1/x)(1/x)? [#permalink]
101
GRE Instructor Joined: 10 Apr 2015
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Re: If x = 10^-1, what is the value of (x + 1/x)(1/x)? [#permalink]
Expert's post
Bunuel wrote:
If $$x = 10^{-1}$$, what is the value of $$(x + \frac{1}{x})(\frac{1}{x})$$?

OA:
[Reveal] Spoiler:
101

Nice rule: 1/(a/b) = b/a
So, for example, 1/(2/3) = 3/2
And 1/(1/10) = 10

GIVEN: x = 10^(-1) = 1/10

So. let's take (x + 1/x)(1/x) and replace x with 1/10

We get: = (x + 1/x)(1/x) = [1/10 + 1/(1/10)][1/(1/10)]
= (1/10 + 10)(10) [after we apply above rule]
= 1 + 100 [after we expand]
= 101

Cheers,
Brent
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Brent Hanneson – Creator of greenlighttestprep.com Sign up for our free GRE Question of the Day emails Intern Joined: 23 Nov 2017
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Re: If x = 10^-1, what is the value of (x + 1/x)(1/x)? [#permalink]
1
KUDOS
I used the exponent rules for this one.

(10^-1 + 1/10^-1)(1/10^-1)
(10^-1 + (10^-1)^-1))((10^-1)^-1)
(10^-1 + 10)(10)
(0.1 + 10)(10)
(10.1)(10)
101 Re: If x = 10^-1, what is the value of (x + 1/x)(1/x)?   [#permalink] 27 Feb 2018, 14:51
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