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If f(w) = (1/w) + 1\(w+8) and the function f(w) equals 1/(w-1) then a

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If f(w) = (1/w) + 1\(w+8) and the function f(w) equals 1/(w-1) then a  [#permalink]

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New post Updated on: 15 Oct 2017, 01:41
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Question Stats:

79% (01:35) correct 21% (01:44) wrong based on 52 sessions

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If \(f(w) =\frac{1}{w} + \frac{1}{w+8}\) and the function f(w) equals \(\frac{1}{w-1}\), then a possible value for w could be

A) -8
B) -4
C) -2
D) -1
E) 3

(Source: Princeton Review GMAT Practice Test 6)

Originally posted by aashaybaindurgmat on 14 Oct 2017, 22:54.
Last edited by Bunuel on 15 Oct 2017, 01:41, edited 2 times in total.
Renamed the topic and edited the question.
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Re: If f(w) = (1/w) + 1\(w+8) and the function f(w) equals 1/(w-1) then a  [#permalink]

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New post 14 Oct 2017, 23:01
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aashaybaindurgmat wrote:
If f(w) =\(\frac{1}{w} + \frac{1}{w+8}\)and the function f(w) equals \(\frac{1}{w-1}\) , then a possible value for w could be

A) -8
B) -4
C) -2
D) -1
E) 3

(Source: Princeton Review GMAT Practice Test 6)


given \(\frac{1}{w}+\frac{1}{(w+8)} = \frac{1}{(w-1)}\)

solve this to get: \(w^2-2w-8=0\)

or \((w-4)(w+2)=0\)

so \(w=4\) or \(-2\)

From the given options only possible value is \(-2\)

Option C

Hi aashaybaindurgmat

kindly rename the subject or ask any moderator to do it, if you are facing any difficulty.
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Re: If f(w) = (1/w) + 1\(w+8) and the function f(w) equals 1/(w-1) then a  [#permalink]

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New post 18 Oct 2017, 00:03
or plugin answer choices.
given 1/w+1/(w+8)=1/(w−1)
let us start with c ie w=-2
-1/2+1/(-2+8)=1/(-2-1)
-1/2+1/6=-1/3
-1/3=-1/3 answer c
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Re: If f(w) = (1/w) + 1\(w+8) and the function f(w) equals 1/(w-1) then a  [#permalink]

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New post 18 Oct 2017, 00:09
or plugin answer choices.

given \(\frac{1}{w}\)+\(\frac{1}{(w+8)}\)=\(\frac{1}{(w−1)}\)

let us start with c ie w=-2

\(\frac{-1}{2}\)+\(\frac{1}{{-2+8}}\)=\(\frac{1}{(-2-1)}\)

\(\frac{-1}{2}\)+\(\frac{1}{6}\)=\(\frac{-1}{3}\)

\(\frac{-1}{3}\)=\(\frac{-1}{3}\) answer c
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If f(w) = (1/w) + 1\(w+8) and the function f(w) equals 1/(w-1) then a  [#permalink]

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New post 20 Oct 2017, 08:26
aashaybaindurgmat wrote:
If \(f(w) =\frac{1}{w} + \frac{1}{w+8}\) and the function f(w) equals \(\frac{1}{w-1}\), then a possible value for w could be

A) -8
B) -4
C) -2
D) -1
E) 3

(Source: Princeton Review GMAT Practice Test 6)

This math just looks time-consuming. It is not. Numbers are easy.*

\(f(w) =\frac{1}{w} + \frac{1}{w+8}\)

And \(f(w) = \frac{1}{w-1}\). Set them equal.

\(\frac{1}{w-1} = \frac{1}{w} + \frac{1}{w+8}\)*

\(\frac{1}{w-1} =
\frac{(w+8)+w}{w(w+8)}\)

\(\frac{1}{(w-1)} =
\frac{2w+8}{w^2+8w}\)

\((2w+8)(w-1) = w^2 + 8w\)

\(2w^2 - 2w + 8w - 8 = w^2 + 8w\)

\(w^2 - 2w - 8 = 0\)

\((w - 4)(w + 2) = 0\)

\(w = 4\) or \(w = -2\)

First option is not a choice. w = -2

Answer C

*Use \(\frac{1}{a} + \frac{1}{b} = \frac{a + b}{ab}\)
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If f(w) = (1/w) + 1\(w+8) and the function f(w) equals 1/(w-1) then a &nbs [#permalink] 20 Oct 2017, 08:26
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