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If ab not equal to 0, then a^(-1) + b^(-1) =

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If ab not equal to 0, then a^(-1) + b^(-1) =  [#permalink]

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New post Updated on: 06 Aug 2019, 00:05
00:00
A
B
C
D
E

Difficulty:

  15% (low)

Question Stats:

92% (00:28) correct 8% (00:37) wrong based on 13 sessions

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If ab not equal to 0, then \(a^{-1} + b^{-1}=\)

A. a + b
B. -(a + b)
C. 1/(a + b)
D. 2/(a + b)
E. (a + b)/ab

Originally posted by carbazzy on 05 Aug 2019, 13:24.
Last edited by Bunuel on 06 Aug 2019, 00:05, edited 2 times in total.
Renamed the topic and edited the question.
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Re: If ab not equal to 0, then a^(-1) + b^(-1) =  [#permalink]

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New post 05 Aug 2019, 13:32
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Top Contributor
You might want to recheck your post.
I think you meant to write "a" instead of "2"

Cheers,
Brent
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Re: If ab not equal to 0, then a^(-1) + b^(-1) =  [#permalink]

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New post 05 Aug 2019, 13:38
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Top Contributor
carbazzy wrote:
If ab not equal to 0, then \(a^-1 + b^-1\) =

a)a+b
b)-(a+b)
c)\(1/a+b\)
d)\(2/a+b\)
e)\(a+b/ab\)


Key concept: \(x^{-n}=\frac{1}{x^n}\)

\(a^{-1} + b^{-1} = \frac{1}{a}+\frac{1}{b}\)

\(= \frac{b}{ab}+\frac{a}{ab}\)

\(= \frac{b+a}{ab}\)

Answer: E

Cheers,
Brent
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Re: If ab not equal to 0, then a^(-1) + b^(-1) =  [#permalink]

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New post 05 Aug 2019, 13:41
a^-1=1/a
==》 1/a + 1/b=a+b/ ab
Option E

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Re: If ab not equal to 0, then a^(-1) + b^(-1) =  [#permalink]

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New post 05 Aug 2019, 13:45
1/b + 1/a = (a + b) / ab

Answer is (E)

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Re: If ab not equal to 0, then a^(-1) + b^(-1) =  [#permalink]

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New post 05 Aug 2019, 13:52
carbazzy wrote:
If ab not equal to 0, then \(a^-1 + b^-1\) =

a)a+b
b)-(a+b)
c)\(1/a+b\)
d)\(2/a+b\)
e)\(a+b/ab\)




Thanks so much for all the replies. Made a ton of silly mistakes today!
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Joined: 30 Sep 2017
Posts: 225
Concentration: Technology, Entrepreneurship
GMAT 1: 720 Q49 V40
GPA: 3.8
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Re: If ab not equal to 0, then a^(-1) + b^(-1) =  [#permalink]

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New post 05 Aug 2019, 14:02
carbazzy wrote:
carbazzy wrote:
If ab not equal to 0, then \(a^-1 + b^-1\) =

a)a+b
b)-(a+b)
c)\(1/a+b\)
d)\(2/a+b\)
e)\(a+b/ab\)




Thanks so much for all the replies. Made a ton of silly mistakes today!


Try this carbazzy

You will definitely enhance your quantitative skill. https://gmatclub.com/forum/a-4-b-3-16-h ... 02011.html

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Re: If ab not equal to 0, then a^(-1) + b^(-1) =   [#permalink] 05 Aug 2019, 14:02
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