GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 22 Sep 2019, 19:50 ### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

#### Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here. ### Request Expert Reply # If 1/c - 1/(c + 3) = 1/(c + 5), then c could be

 new topic post reply Question banks Downloads My Bookmarks Reviews Important topics
Author Message
TAGS:

### Hide Tags

Math Expert V
Joined: 02 Sep 2009
Posts: 58098
If 1/c - 1/(c + 3) = 1/(c + 5), then c could be  [#permalink]

### Show Tags 00:00

Difficulty:   15% (low)

Question Stats: 96% (01:56) correct 4% (02:09) wrong based on 27 sessions

### HideShow timer Statistics

If 1/c - 1/(c + 3) = 1/(c + 5), then c could be

A. $$\sqrt{15}$$
B. 1
C. 0
D. -1
E. -7

_________________
Senior Manager  P
Joined: 30 Sep 2017
Posts: 344
Concentration: Technology, Entrepreneurship
GMAT 1: 720 Q49 V40 GPA: 3.8
WE: Engineering (Real Estate)
If 1/c - 1/(c + 3) = 1/(c + 5), then c could be  [#permalink]

### Show Tags

1/c - 1/(c + 3) = 1/(c + 5)

try c value given in each option and put that value into the above equation. We easily find that Options (B) to (E) are wrong.
A. √15 --> skip
B. 1 --> 1 - 1/4 = 1/6 (No!)
C. 0 --> 1/0 - ... (No!)
D. -1 --> - 1 - 1/2 = 1/4 (No!)
E. -7 --> -1/7 + 1/4 = -1/2 (No!)

Posted from my mobile device
Senior Manager  P
Joined: 13 Jan 2018
Posts: 344
Location: India
Concentration: Operations, General Management
GMAT 1: 580 Q47 V23 GMAT 2: 640 Q49 V27 GPA: 4
WE: Consulting (Consulting)
Re: If 1/c - 1/(c + 3) = 1/(c + 5), then c could be  [#permalink]

### Show Tags

1
$$\frac{1}{c} - \frac{1}{(c + 3)}$$ = $$\frac{1}{(c + 5)}$$

$$\frac{3}{c(c + 3)}$$ = $$\frac{1}{(c + 5)}$$

$$3c + 15 = c^2 + 3c$$

c = $$\sqrt{15}$$

OPTION: A
_________________
____________________________
Regards,

Chaitanya

+1 Kudos

if you like my explanation!!!
Senior Manager  S
Joined: 29 Jun 2019
Posts: 327
Re: If 1/c - 1/(c + 3) = 1/(c + 5), then c could be  [#permalink]

### Show Tags

c+3-c /c^2+3c = 1/c+5
c^2 + 3c=3c+15
c^2=15
c=√15
Option A

Posted from my mobile device
_________________
Always waiting
Target Test Prep Representative D
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 7777
Location: United States (CA)
Re: If 1/c - 1/(c + 3) = 1/(c + 5), then c could be  [#permalink]

### Show Tags

1
Bunuel wrote:
If 1/c - 1/(c + 3) = 1/(c + 5), then c could be

A. $$\sqrt{15}$$
B. 1
C. 0
D. -1
E. -7

We clear all fractions in the equation by multiplying the entire equation by c(c+3)(c+5), obtaining:

(c+3)(c+5) - c(c+5) = c(c+3)

c^2 + 8c + 15 - c^2 - 5c = c^2 + 3c

c^2 = 15

c = ±√15

_________________

# Scott Woodbury-Stewart

Founder and CEO

Scott@TargetTestPrep.com

See why Target Test Prep is the top rated GMAT quant course on GMAT Club. Read Our Reviews

If you find one of my posts helpful, please take a moment to click on the "Kudos" button. Re: If 1/c - 1/(c + 3) = 1/(c + 5), then c could be   [#permalink] 24 Aug 2019, 05:27
Display posts from previous: Sort by

# If 1/c - 1/(c + 3) = 1/(c + 5), then c could be

 new topic post reply Question banks Downloads My Bookmarks Reviews Important topics

 Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne  