GMAT Question of the Day: Daily via email | Daily via Instagram New to GMAT Club? Watch this Video
close
It is currently 19 Jan 2022, 18:17
Register
GMAT Club Tests
Decision Tracker
My Rewards
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
If a is a positive integer then 3^(2a) + 36^a/2^(2a) =
8 posts Go to First Unread Post
Print view
NEW TOPIC
POST REPLY
Downloads
My Bookmarks
Reviews
SORT BY:
Date
Kudos
Tags:
Find Similar Topics 

Show Tags
Hide Tags

User avatar
V
Bunuel
Math Expert
Joined: 02 Sep 2009
Posts: 83881
Premium Member CAT Tests Forum Quiz Mode Top Member of the Month
If a is a positive integer then 3^(2a) + 36^a/2^(2a) = [#permalink] New post  15 Jul 2015, 02:12
1
Kudos
9
Bookmarks
Expert Reply
Quiz Dashboard Attempt only this question Same topic and source Same topic and difficulty Same source and difficulty Random Chronological Reverse chronological Learn more
00:00
A
B
C
D
E

Difficulty:

45% (medium)

Question Stats:

69% (01:44) correct 31% (02:30) wrong based on 283 sessions

Hide Show timer Statistics

If a is a positive integer then 3^(2a) + (36^a)/(2^(2a)) =

A. (9/4)^a + 9^a
B. 9^a + 18^a
C. 18^a
D. 0
E. 2 × 9^a

Kudos for a correct solution.
ShowHide Answer
Official Answer
Official Answer and Stats are available only to registered users. Register/Login.

_________________
New to the GMAT CLUB Forum?

My Signature Questions' Collection:


What are GMAT Club Tests?
Extra-hard Quant Tests with Brilliant Analytics
Signature Read More
Quiz Dashboard Attempt only this question Same topic and source Same topic and difficulty Same source and difficulty Random Chronological Reverse chronological Learn more
avatar
sanket1991
Manager
Manager
Joined: 13 Sep 2014
Posts: 81
WE:Engineering (Consulting)
Re: If a is a positive integer then 3^(2a) + 36^a/2^(2a) = [#permalink] New post  15 Jul 2015, 03:06
3^(2a) + 36^a/2^(2a) = 9^a + (9^a*4^a/ 4^a) = 9^a + 9^a = 2*9^a
avatar
G
ENGRTOMBA2018
SVP
SVP
Joined: 20 Mar 2014
Posts: 2461
Concentration: Finance, Strategy
Schools: Kellogg '18 (M)
GMAT 1: 750 Q49 V44
GPA: 3.7
WE:Engineering (Aerospace and Defense)
GMAT ToolKit User Reviews Badge
Re: If a is a positive integer then 3^(2a) + 36^a/2^(2a) = [#permalink] New post  15 Jul 2015, 03:36
3
Kudos
1
Bookmarks
Bunuel wrote:
If a is a positive integer then 3^(2a) + 36^a/2^(2a) =

A. (9/4)^a + 9^a
B. 9^a + 18^a
C. 18^a
D. 0
E. 2 × 9^a

Kudos for a correct solution.


I am quoting the same question with a bit more formatting:

\(3^{2a} + \frac{36^a}{2^{2a}}\) ----> Let go of the variables and plug in a =1 as this statement must be true for all values of a (even 0).

Thus with a =1 we get, \(3^{2} + \frac{36^1}{2^{2}}\) = 2* 9 =18---> Now plug in a =1 in the options and we see that options C and E satisfy this. To eliminate C, use a =0. Thus E is the correct answer.
_________________
My Kellogg Journey (2016-2018): https://gmatclub.com/forum/my-kellogg-journey-325661.html
Thursday with Ron updated list as of July 1st, 2015: http://gmatclub.com/forum/consolidated-thursday-with-ron-list-for-all-the-sections-201006.html#p1544515
Rules for Posting in Quant Forums: http://gmatclub.com/forum/rules-for-posting-please-read-this-before-posting-133935.html
Writing Mathematical Formulae in your posts: http://gmatclub.com/forum/rules-for-posting-please-read-this-before-posting-133935.html#p1096628
GMATCLUB Math Book: http://gmatclub.com/forum/gmat-math-book-in-downloadable-pdf-format-130609.html
Everything Related to Inequalities: http://gmatclub.com/forum/inequalities-made-easy-206653.html#p1582891
Inequalities tips: http://gmatclub.com/forum/inequalities-tips-and-hints-175001.html
Debrief, 650 to 750: http://gmatclub.com/forum/650-to-750-a-10-month-journey-to-the-score-203190.html
Signature Read More
avatar
ashokk138
Manager
Manager
Joined: 20 Jul 2011
Posts: 75
GMAT 1: 660 Q49 V31
GMAT ToolKit User
Re: If a is a positive integer then 3^(2a) + 36^a/2^(2a) = [#permalink] New post  17 Jul 2015, 22:46
1
Bookmarks
Bunuel wrote:
If a is a positive integer then 3^(2a) + 36^a/2^(2a) =

A. (9/4)^a + 9^a
B. 9^a + 18^a
C. 18^a
D. 0
E. 2 × 9^a

Kudos for a correct solution.


Given:
3^(2a) can be written as 9^a
Similarly,2^(2a) can be written as 4^a

Rearranging the eq:

9^a + (36^a / 4^a) => 9^a + (36/4) ^ a => 9^a + 9^a => 2 x 9^a.

Option E
avatar
ashokk138
Manager
Manager
Joined: 20 Jul 2011
Posts: 75
GMAT 1: 660 Q49 V31
GMAT ToolKit User
Re: If a is a positive integer then 3^(2a) + 36^a/2^(2a) = [#permalink] New post  17 Jul 2015, 22:47
Bunuel wrote:
If a is a positive integer then 3^(2a) + 36^a/2^(2a) =

A. (9/4)^a + 9^a
B. 9^a + 18^a
C. 18^a
D. 0
E. 2 × 9^a

Kudos for a correct solution.


Given:
3^(2a) can be written as 9^a
Similarly,2^(2a) can be written as 4^a

Rearranging the eq:

9^a + (36^a / 4^a) => 9^a + (36/4) ^ a => 9^a + 9^a => 2 x 9^a.

Option E
User avatar
V
Bunuel
Math Expert
Joined: 02 Sep 2009
Posts: 83881
Premium Member CAT Tests Forum Quiz Mode Top Member of the Month
Re: If a is a positive integer then 3^(2a) + 36^a/2^(2a) = [#permalink] New post  19 Jul 2015, 12:14
Expert Reply
Bunuel wrote:
If a is a positive integer then 3^(2a) + 36^a/2^(2a) =

A. (9/4)^a + 9^a
B. 9^a + 18^a
C. 18^a
D. 0
E. 2 × 9^a

Kudos for a correct solution.


800score Official Solution:

3^(2a) + 36^a/ 2^(2a) = 9^a + 36^a/4^a = 9^a + (36/4)^a = 9^a + 9^a = 2 × 9^a, choice (E).

Plugging in different values for a until all choices except one are eliminated is also an option.
_________________
New to the GMAT CLUB Forum?

My Signature Questions' Collection:


What are GMAT Club Tests?
Extra-hard Quant Tests with Brilliant Analytics
Signature Read More
User avatar
P
mvictor
Board of Directors
Joined: 17 Jul 2014
Posts: 2296
Location: United States (IL)
Concentration: Finance, Economics
Schools: Stanford '20 (WD)
GMAT 1: 650 Q49 V30
GPA: 3.92
WE:General Management (Transportation)
GMAT ToolKit User Reviews Badge
If a is a positive integer then 3^(2a) + 36^a/2^(2a) = [#permalink] New post  30 Dec 2015, 19:53
the fraction can be rewritten as:
(4*9)^a/2^2a

now, numerator can be rewritten as:
2^2a * 3^2a / 2^2a.

simplify 2^2a from numerator and denominator

we are left with 3^2a * 3^2a
rewrite 3^2a(1+1)
3^2a(2)
since no answer matches, let's raise 3 to the second power:
9^a * 2
E is the answer.

redone the question sept 9/28/16
same approach used.
User avatar
V
stne
VP
VP
Joined: 27 May 2012
Posts: 1388
Re: If a is a positive integer then 3^(2a) + 36^a/2^(2a) = [#permalink] New post  30 Jun 2018, 03:54
Bunuel wrote:
If a is a positive integer then 3^(2a) + (36^a)/(2^(2a)) =

A. (9/4)^a + 9^a
B. 9^a + 18^a
C. 18^a
D. 0
E. 2 × 9^a

Kudos for a correct solution.


Thought the question to be : \(\frac{3^{2a} + 36^a}{2^{2a}}\)and ended up getting A.

Question actually means \(3^{2a} + \frac{36^a}{2^{2a}}\)

Perhaps moderator could format in a different way to make the question less confusing. Thank you.
_________________
- Stne
Signature Read More
GMAT Club Bot
gmatclubot
Re: If a is a positive integer then 3^(2a) + 36^a/2^(2a) = [#permalink]
30 Jun 2018, 03:54
NEW TOPIC
POST REPLY
Downloads
My Bookmarks
Reviews
Moderators:
chetan2u
Math Expert
10669 posts
Bunuel
Math Expert
83881 posts
yashikaaggarwal
Senior Moderator - Masters Forum
2853 posts
generis
Senior SC Moderator
5244 posts

cron

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

Main navigation

GMAT Resources

Partners

MBA Resources

www.gmac.com|www.mba.com | | GMAT Club Rules | Terms and Conditions