Last visit was: 31 Oct 2024, 16:52 It is currently 31 Oct 2024, 16:52
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.
Close
Request Expert Reply
Confirm Cancel
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 31 Oct 2024
Posts: 96,533
Own Kudos:
Given Kudos: 87,883
Products:
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 96,533
Kudos: 673,100
 [19]
1
Kudos
Add Kudos
18
Bookmarks
Bookmark this Post
Most Helpful Reply
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 31 Oct 2024
Posts: 96,533
Own Kudos:
Given Kudos: 87,883
Products:
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 96,533
Kudos: 673,100
 [13]
4
Kudos
Add Kudos
9
Bookmarks
Bookmark this Post
General Discussion
User avatar
askhere
Joined: 12 Nov 2014
Last visit: 31 Oct 2024
Posts: 64
Own Kudos:
203
 [2]
Given Kudos: 14
Posts: 64
Kudos: 203
 [2]
2
Kudos
Add Kudos
Bookmarks
Bookmark this Post
avatar
NavenRk
Joined: 01 Jan 2015
Last visit: 02 Oct 2019
Posts: 16
Own Kudos:
33
 [3]
Given Kudos: 7
Posts: 16
Kudos: 33
 [3]
2
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
1 + x^4 + x^3 + x^2 + x = 81

multiplying by 'x' on both sides

x(1 + x^4 + x^3 + x^2 + x )= 81x

dividing by 5 we get

x+ x^2+ x^3+ x^4+x^5 = 81x/5 Approx 16x
But is approximation allowed? i don't see it mentioned in the question?
User avatar
askhere
Joined: 12 Nov 2014
Last visit: 31 Oct 2024
Posts: 64
Own Kudos:
Given Kudos: 14
Posts: 64
Kudos: 203
Kudos
Add Kudos
Bookmarks
Bookmark this Post
NavenRk
1 + x^4 + x^3 + x^2 + x = 81

multiplying by 'x' on both sides

x(1 + x^4 + x^3 + x^2 + x )= 81x

dividing by 5 we get

x+ x^2+ x^3+ x^4+x^5 = 81x/5 Approx 16x
But is approximation allowed? i don't see it mentioned in the question?


Ohh yeah. This is a much easier way. Kudos!
I think the question meant approximate value.
User avatar
D3N0
Joined: 21 Jan 2015
Last visit: 22 Oct 2024
Posts: 421
Own Kudos:
361
 [1]
Given Kudos: 82
Location: India
Concentration: Strategy, Marketing
GMAT 1: 620 Q48 V28
GMAT 2: 690 Q49 V35
WE:Sales (Consumer Packaged Goods)
Products:
GMAT 1: 620 Q48 V28
GMAT 2: 690 Q49 V35
Posts: 421
Kudos: 361
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Bunuel
If 1 + x^4 + x^3 + x^2 + x = 81, then the average (arithmetic mean) of x, x^2, x^3, x^4 and x^5 is equal to which of the following?

A. 12x
B. 13x
C. 14x
D. 16x
E. 20x

Kudos for a correct solution.

Ans: D

Solution: [x + x^2 + x^3 + x^4 + x^5]/5
Known 1 + x^4 + x^3 + x^2 + x = 81
taking x common from the first equation it becomes
=[1 + x^4 + x^3 + x^2 + x]*x/5
=81*x/5
=16x Answer
Ans.: D
User avatar
bumpbot
User avatar
Non-Human User
Joined: 09 Sep 2013
Last visit: 04 Jan 2021
Posts: 35,331
Own Kudos:
Posts: 35,331
Kudos: 902
Kudos
Add Kudos
Bookmarks
Bookmark this Post
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.
Moderator:
Math Expert
96533 posts