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If a-b/a+b

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If a-b/a+b =2 and b=1, what is the value of a ? [#permalink]  24 Feb 2017, 02:55
Expert's post
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Question Stats:

100% (00:27) correct 0% (00:00) wrong based on 5 sessions

If $$\frac{a-b}{a+b} = 2$$ and $$b=1$$, what is the value of a ?

A) 1

B) 0

C) -1

D) -2

E) -3
[Reveal] Spoiler: OA

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GRE 1: Q167 V156
WE: Business Development (Energy and Utilities)
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Re: If a-b/a+b =2 and b=1, what is the value of a ? [#permalink]  03 Mar 2017, 06:13
1
KUDOS
Expert's post
Explanation

Here we have the expression $$\frac{a-b}{a+b} = 2$$ and also given that $$b=1$$.

Putting value of b in the expression.

$$\frac{a-b}{a+b} = 2$$

or $$\frac{a-1}{a+1} = 2$$ or $$a-1 = 2a + 2$$ or $$a = -3$$.

Hence E is the correct option.
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Sandy
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Re: If a-b/a+b =2 and b=1, what is the value of a ? [#permalink]  28 Mar 2017, 17:19
1
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Expert's post
Carcass wrote:

If $$\frac{a - b}{a + b} = 2$$ and $$b = 1$$, what is the value of a ?

A) 1

B) 0

C) -1

D) -2

E) -3

If b = 1, let's first replace b with 1 to get: (a - 1)/(a + 1) = 2
Multiply both sides of the equation by (a+1) to get: a - 1 = 2(a + 1)
Simplify: a - 1 = 2a + 2
Subtract a from both sides: -1 = a + 2
Subtract 2 from both sides: -3 = a

[Reveal] Spoiler:
E

Cheers,
Brent
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Brent Hanneson – Creator of greenlighttestprep.com

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Re: If a-b/a+b [#permalink]  22 Nov 2017, 11:27
Expert's post
Explanation

Whenever you see such question the fastest way is to plug in the answer choices. Start almost always from the bottom, which means E

$$\frac{-3-1}{-3+1}= \frac{-4}{-2}=2$$

E wins
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Re: If a-b/a+b   [#permalink] 22 Nov 2017, 11:27
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