Last visit was: 11 Sep 2024, 20:00 It is currently 11 Sep 2024, 20:00
Decision Tracker
My Rewards
Unanswered
Active Topics
New posts
New comers' posts
Close
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
Your Progress

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.
Go to My Error Log Learn more
Close
Request Expert Reply
Confirm Cancel

Multiplying which of the following by the nonzero number (5 - 2x)/7

SORT BY:
Date
Kudos
Tags:
Find Similar Topics 
Show Tags
Hide Tags
User avatar
L
Bunuel
Math Expert
Joined: 02 Sep 2009
Posts: 95451
Own Kudos [?]: 657763 [2]
Given Kudos: 87242
Send PM
CAT Tests Forum Quiz Mode
Multiplying which of the following by the nonzero number (5 - 2x)/7 [#permalink] Multiplying which of the following by the nonzero number (5 - 2x)/7   22 Nov 2019, 03:31
2
Bookmarks
Expert Reply
00:00
A
B
C
D
E

Difficulty:

15% (low)

Question Stats:

72% (00:58) correct 28% (01:19) wrong based on 139 sessions
Hide Show DIFFICULTY AND TIMER STATISTICS
Multiplying which of the following by the nonzero number \(\frac{5-2x}{7}\) will give you a product of \(-1\)?

A. \(\frac{7}{5-2x}\)

B. \(\frac{-7}{2x-5}\)

C. \(\frac{7}{2x-5}\)

D. \(\frac{2x-5}{7}\)

E. \(7(2x-5)\)
ShowHide Answer
Official Answer
C
User avatar
L
BrentGMATPrepNow
GMAT Club Legend
GMAT Club Legend
Joined: 12 Sep 2015
Posts: 6803
Own Kudos [?]: 31273 [1]
Given Kudos: 799
Location: Canada
Send PM
Re: Multiplying which of the following by the nonzero number (5 - 2x)/7 [#permalink] Multiplying which of the following by the nonzero number (5 - 2x)/7   22 Nov 2019, 08:25
1
Kudos
Expert Reply
Top Contributor
Bunuel
Multiplying which of the following by the nonzero number \(\frac{5-2x}{7}\) will give you a product of \(-1\)?

A. \(\frac{7}{5-2x}\)

B. \(\frac{-7}{2x-5}\)

C. \(\frac{7}{2x-5}\)

D. \(\frac{2x-5}{7}\)

E. \(7(2x-5)\)

Useful property: \((\frac{b}{c})(\frac{c}{b})=1\)

Let \(k\) = the desired value.

So, we want: \((\frac{5-2x}{7})(k) = -1\)

Multiply both sides by \(\frac{7}{5-2x}\) to get: : \((\frac{7}{5-2x})(\frac{5-2x}{7})(k) = (-1)(\frac{7}{5-2x})\)

Apply above property to get: \((1)(k) = (-1)(\frac{7}{5-2x})\)

From here, it's useful to scan the answer choices to see what format they want.

It looks like we can apply another use property, which says \((-1)(a - b) = b - a\)

So, take the last given equation and rewrite it as follows: \(k = (\frac{1}{-1})(\frac{7}{5-2x})\)

Multiply the numerators and denominators to get: \(k=\frac{7}{2x-5}\)

Answer: C

Cheers,
Brent
User avatar
bumpbot
Non-Human User
Joined: 09 Sep 2013
Posts: 34818
Own Kudos [?]: 877 [0]
Given Kudos: 0
Send PM
Re: Multiplying which of the following by the nonzero number (5 - 2x)/7 [#permalink] Multiplying which of the following by the nonzero number (5 - 2x)/7   21 Aug 2021, 05:50
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
GMAT Club Bot
gmatclubot
Re: Multiplying which of the following by the nonzero number (5 - 2x)/7 [#permalink]
21 Aug 2021, 05:50
Moderator:
Bunuel
Math Expert
95451 posts