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

It is currently 17 Oct 2018, 07:43

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

Suppose y=2^x^2+2^x+3. Which of these x-values gives the s

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

Hide Tags

Math Revolution GMAT Instructor
User avatar
V
Joined: 16 Aug 2015
Posts: 6375
GMAT 1: 760 Q51 V42
GPA: 3.82
Premium Member
Suppose y=2^x^2+2^x+3. Which of these x-values gives the s  [#permalink]

Show Tags

New post 16 Mar 2018, 00:56
00:00
A
B
C
D
E

Difficulty:

  25% (medium)

Question Stats:

71% (01:25) correct 29% (01:42) wrong based on 98 sessions

HideShow timer Statistics

[GMAT math practice question]

Suppose \(y=2^{x^2}+2^{x+3}\). Which of these \(x\)-values gives the smallest value of \(y\)?

A. -3
B. -2
C. -1
D. 1
E. 2

_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
"Only $99 for 3 month Online Course"
"Free Resources-30 day online access & Diagnostic Test"
"Unlimited Access to over 120 free video lessons - try it yourself"

CEO
CEO
User avatar
P
Joined: 08 Jul 2010
Posts: 2537
Location: India
GMAT: INSIGHT
WE: Education (Education)
Reviews Badge
Re: Suppose y=2^x^2+2^x+3. Which of these x-values gives the s  [#permalink]

Show Tags

New post 16 Mar 2018, 01:20
MathRevolution wrote:
[GMAT math practice question]

Suppose \(y=2^{x^2}+2^{x+3}\). Which of these \(x\)-values gives the smallest value of \(y\)?

A. -3
B. -2
C. -1
D. 1
E. 2




A. -3 y = 2^9 + 2^0 = 513
B. -2 y = 2^4 + 2^1 = 17
C. -1 y = 2^1 + 2^2 = 5
D. 1 y = 2^1 + 2^4 = 18
E. 2 y = 2^4 + 2^5 = 48

Answer: option C
_________________

Prosper!!!
GMATinsight
Bhoopendra Singh and Dr.Sushma Jha
e-mail: info@GMATinsight.com I Call us : +91-9999687183 / 9891333772
Online One-on-One Skype based classes and Classroom Coaching in South and West Delhi
http://www.GMATinsight.com/testimonials.html

ACCESS FREE GMAT TESTS HERE:22 ONLINE FREE (FULL LENGTH) GMAT CAT (PRACTICE TESTS) LINK COLLECTION

Math Revolution GMAT Instructor
User avatar
V
Joined: 16 Aug 2015
Posts: 6375
GMAT 1: 760 Q51 V42
GPA: 3.82
Premium Member
Re: Suppose y=2^x^2+2^x+3. Which of these x-values gives the s  [#permalink]

Show Tags

New post 18 Mar 2018, 23:21
=>

Since the exponent function \(y=2^x\) is an increasing function, the smallest value of \(x^2+2x+3\) gives the smallest value of \(y=2^{x^2}+2^{x+3}\).
Since \(x^2+2x+3 = (x+1)^2 + 2\), the exponent \((x+1)^2 + 2\) has a minimum value when \(x = -1\).

Therefore, the answer is C.
Answer : C
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
"Only $99 for 3 month Online Course"
"Free Resources-30 day online access & Diagnostic Test"
"Unlimited Access to over 120 free video lessons - try it yourself"

Intern
Intern
avatar
B
Joined: 11 Feb 2016
Posts: 12
Re: Suppose y=2^x^2+2^x+3. Which of these x-values gives the s  [#permalink]

Show Tags

New post 04 Apr 2018, 04:56
Could someone explain me why 2^(-3)^2 does not equal 2^(-6)?
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 49968
Re: Suppose y=2^x^2+2^x+3. Which of these x-values gives the s  [#permalink]

Show Tags

New post 04 Apr 2018, 05:35
PedroBodnar wrote:
Could someone explain me why 2^(-3)^2 does not equal 2^(-6)?


\(a^m^n=a^{(m^n)}\) and not \((a^m)^n\) (if exponentiation is indicated by stacked symbols, the rule is to work from the top down). Thus, \(2^{(-3)^2}=2^{((-3)^2)}=2^9\) and not \((2^{(-3)})^2=2^{-6}\)

On the other hand, \((a^m)^n=a^{mn}\).

8. Exponents and Roots of Numbers



Check below for more:
ALL YOU NEED FOR QUANT ! ! !
Ultimate GMAT Quantitative Megathread
_________________

New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

Collection of Questions:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
Extra-hard Quant Tests with Brilliant Analytics

GMAT Club Bot
Re: Suppose y=2^x^2+2^x+3. Which of these x-values gives the s &nbs [#permalink] 04 Apr 2018, 05:35
Display posts from previous: Sort by

Suppose y=2^x^2+2^x+3. Which of these x-values gives the s

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


Copyright

GMAT Club MBA Forum Home| About| Terms and Conditions and Privacy Policy| GMAT Club Rules| Contact| Sitemap

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

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.