Last visit was: 24 Apr 2026, 18:16 It is currently 24 Apr 2026, 18:16
Home
Messages
Tests
Schools
Events
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
Back to Forum
Create Topic
505-555 (Easy)|   Exponents|         
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 24 Apr 2026
Posts: 109,818
Own Kudos:
811,083
 [6]
Given Kudos: 105,873
Products:
GMAT Club Tests Forum Quiz
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 109,818
Kudos: 811,083
 [6]
HOT Competition: If 3^b – (3^8 + 3^6) = 0, what is the approximate val 24 Aug 2020, 20:00
Kudos
Add Kudos
6
Bookmarks
Bookmark this Post
00:00
Start Timer
Pause Timer
Resume Timer
Show Answer
Hide
Show
History
B
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!

Difficulty:

15% (low)

Question Stats:

76% (01:26) correct 24% (01:35) wrong based on 666 sessions

History

Date
Time
Result
Not Attempted Yet
If \(3^b – (3^8 + 3^6) = 0\), what is the approximate value of b?

A. 5
B. 8
C. 10
D. 12
E. 14


 

This question was provided by Crack Verbal
for the Heroes of Timers Competition

 

ShowHide Answer
Official Answer
B
User avatar
yashikaaggarwal
User avatar
Senior Moderator - Masters Forum
Joined: 19 Jan 2020
Last visit: 29 Mar 2026
Posts: 3,089
Own Kudos:
3,158
 [3]
Given Kudos: 1,510
Location: India
Schools: Cranfield (A) Warwick MiM "23 (M)
GPA: 4
WE:Analyst (Internet and New Media)
Schools: Cranfield (A) Warwick MiM "23 (M)
Posts: 3,089
Kudos: 3,158
 [3]
HOT Competition: If 3^b – (3^8 + 3^6) = 0, what is the approximate val 24 Aug 2020, 20:11
3
Kudos
Add Kudos
Bookmarks
Bookmark this Post
3^b - (3^8+3^6) = 0
3^b - 3^6(3^2+1) = 0
3^b - 3^6(3^2) = 0 {10 is nearest to 9 (3^2) as compared to 27 (3^3) }
3^b = 3^8

Answer is B

Posted from my mobile device
avatar
Ali17
avatar
Joined: 13 Apr 2017
Last visit: 29 Mar 2025
Posts: 2
Own Kudos:
3
 [2]
Given Kudos: 62
Location: India
Schools: IIMC MBAEx'23
GMAT 1: 690 Q50 V34
Schools: IIMC MBAEx'23
GMAT 1: 690 Q50 V34
Posts: 2
Kudos: 3
 [2]
HOT Competition: If 3^b – (3^8 + 3^6) = 0, what is the approximate val 24 Aug 2020, 20:14
2
Kudos
Add Kudos
Bookmarks
Bookmark this Post
3^b - (3^8+3^6) = 0
3^b - 3^6(3^2+1) = 0
3^b = 3^6*10
b = 6+2 (approx)
b = 8

Hence (B)
User avatar
minustark
User avatar
Joined: 14 Jul 2019
Last visit: 01 Apr 2021
Posts: 465
Own Kudos:
402
 [2]
Given Kudos: 52
Status:Student
Location: United States
Concentration: Accounting, Finance
Schools: Zicklin Baruch "22
GMAT 1: 650 Q45 V35
GPA: 3.9
WE:Education (Accounting)
Products:
My Reviews
Schools: Zicklin Baruch "22
GMAT 1: 650 Q45 V35
Posts: 465
Kudos: 402
 [2]
HOT Competition: If 3^b – (3^8 + 3^6) = 0, what is the approximate val 24 Aug 2020, 20:26
2
Kudos
Add Kudos
Bookmarks
Bookmark this Post
3^b -(3^8+3^6) = 0 or, 3^b = 3^8 + 3^6

3^b = 3^6 (3^2 + 1)
3^b = 3^6 * 10...which is approximately 3^2

3^b = 3^ (6+2)
3^b = 3^8

B is the answer.

Posted from my mobile device
User avatar
JonShukhrat
User avatar
Joined: 06 Jun 2019
Last visit: 27 Mar 2026
Posts: 312
Own Kudos:
994
 [2]
Given Kudos: 656
Location: Uzbekistan
Posts: 312
Kudos: 994
 [2]
HOT Competition: If 3^b – (3^8 + 3^6) = 0, what is the approximate val 24 Aug 2020, 21:35
2
Kudos
Add Kudos
Bookmarks
Bookmark this Post
What is the approximate value of b?

\(3^b = (3^8 + 3^6)\)
\(3^b = (3^2 * 3^6 + 3^6)\)
\(3^b = 10 * 3^6\)

So, \(3^b\) must be between B and C. Let’s juxtapose:

\(3^b = 10 * 3^6\)
B. \(3^8 = 9 * 3^6\)
C. \(3^{10} = 81 * 3^6\)

We can see that \(3^b\) is closer to B than to C.

Hence B

Posted from my mobile device
avatar
raunaqkapoor
avatar
Joined: 03 Sep 2019
Last visit: 30 Aug 2020
Posts: 9
Own Kudos:
28
 [3]
Given Kudos: 66
Location: India
WE:Analyst (Retail: E-commerce)
Posts: 9
Kudos: 28
 [3]
HOT Competition: If 3^b – (3^8 + 3^6) = 0, what is the approximate val 24 Aug 2020, 21:41
3
Kudos
Add Kudos
Bookmarks
Bookmark this Post
3^b-(3^8+3^6)
3^b-3^6(9+1)
3^b-3^6*10

10~3*3 ---- 1
3^b-3^8 from 1
hence b=8
User avatar
rahulbhusan
User avatar
Joined: 08 Jan 2020
Last visit: 18 Dec 2021
Posts: 34
Own Kudos:
19
 [2]
Posts: 34
Kudos: 19
 [2]
HOT Competition: If 3^b – (3^8 + 3^6) = 0, what is the approximate val 24 Aug 2020, 21:45
2
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Given, 3^b–(3^8+3^6)=0
=> 3^b= (3^8+3^6)
=> 3^b= 3^6(3^2+1)
=> 3^b= 3^6(10)
=> 3^b= 3^6(9) ( As we need to approximate)
=> 3^b= (3^8)
=> b=8
Option B

We can also quickly verify:
=> 3^b= 3^6(10)
=> 3^b= 729*10
=> 3^b= 7290
Now, 3^8= 6561, and 3^9= 19683 (This is way too big than 7290)
Hence, 3^8 is the best approximate value.
User avatar
kush09
User avatar
Joined: 01 May 2019
Last visit: 25 Aug 2024
Posts: 144
Own Kudos:
159
 [1]
Given Kudos: 27
Location: India
Concentration: General Management, Technology
GMAT 1: 660 Q49 V31
GPA: 3.5
WE:Information Technology (Finance: Investment Banking)
Products:
My Reviews
GMAT 1: 660 Q49 V31
Posts: 144
Kudos: 159
 [1]
HOT Competition: If 3^b – (3^8 + 3^6) = 0, what is the approximate val 25 Aug 2020, 00:07
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Quote:
If 3^b–(3^8+3^6)=0, what is the approximate value of b?
Show more

Solution:
=> 3^b–3^6 (3^2+1)=0
=> 3^b–3^6 (10)=0
=> 3^6 (3^(b-6)–10)=0
divide both side by 3^6
=> 3^(b-6)–10 = 0
=> 3^(b-6) = 10
Consider 10 as 9. As we have been asked approximate value of B.
=> 3^(b-6) = 9
=> 3^(b-6) = 3^2
=> b-6 = 2
=> b = 8
whcih is option B.
User avatar
GKomoku
User avatar
Joined: 06 Mar 2018
Last visit: 23 Mar 2022
Posts: 301
Own Kudos:
957
 [2]
Given Kudos: 3,681
Status:To infinity and beyond
Location: Kazakhstan
Concentration: Technology, Finance
Schools: Stanford '23 Sloan '23
GPA: 3.87
Schools: Stanford '23 Sloan '23
Posts: 301
Kudos: 957
 [2]
HOT Competition: If 3^b – (3^8 + 3^6) = 0, what is the approximate val 25 Aug 2020, 03:35
2
Kudos
Add Kudos
Bookmarks
Bookmark this Post
If \(3^b–(3^8+3^6)=0\), what is the approximate value of b?

A. 5
B. 8
C. 10
D. 12
E. 14



\(3^b–(3^8+3^6)=0\) - expression cannot be simplified further.
questions asks "approximate" value for b.

\(3^8+3^6\) - we don't need to actually calculate this big numbers.
the value will be slightly higher than the 3^8
so b will be something like ~8.121232313
we won't sum up exponents here.

(B) is the answer. :heart
avatar
TomNook
avatar
Joined: 06 Jan 2021
Last visit: 20 May 2022
Posts: 14
Own Kudos:
3
Given Kudos: 50
Posts: 14
Kudos: 3
HOT Competition: If 3^b – (3^8 + 3^6) = 0, what is the approximate val 02 Oct 2021, 18:40
Kudos
Add Kudos
Bookmarks
Bookmark this Post
The trick here is to approximate as it won't be feasible to try to calculate the exact value
User avatar
yashikaaggarwal
User avatar
Senior Moderator - Masters Forum
Joined: 19 Jan 2020
Last visit: 29 Mar 2026
Posts: 3,089
Own Kudos:
3,158
Given Kudos: 1,510
Location: India
Schools: Cranfield (A) Warwick MiM "23 (M)
GPA: 4
WE:Analyst (Internet and New Media)
Schools: Cranfield (A) Warwick MiM "23 (M)
Posts: 3,089
Kudos: 3,158
HOT Competition: If 3^b – (3^8 + 3^6) = 0, what is the approximate val 02 Oct 2021, 19:33
Kudos
Add Kudos
Bookmarks
Bookmark this Post
TomNook
The trick here is to approximate as it won't be feasible to try to calculate the exact value
Show more
You only have to take the approximate value of 3^2+1 that is equal to 10
We know 3^3 = will be way higher than 10 and 3^1 is less than 10
So 3^2 is the only feasible option. Hence it won't take much time to solve question.

Posted from my mobile device
User avatar
bumpbot
User avatar
Non-Human User
Joined: 09 Sep 2013
Last visit: 04 Jan 2021
Posts: 38,975
Own Kudos:
1,117
Posts: 38,975
Kudos: 1,117
HOT Competition: If 3^b – (3^8 + 3^6) = 0, what is the approximate val 16 Oct 2022, 09:08
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Automated notice from GMAT Club BumpBot:

A member just gave Kudos to this thread, showing it’s still useful. I’ve bumped it to the top so more people can benefit. Feel free to add your own questions or solutions.

This post was generated automatically.
Moderators:
Bunuel
Math Expert
109818 posts
Krunaal
Tuck School Moderator
853 posts