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

 It is currently 13 Nov 2018, 08:19

### 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

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

## Events & Promotions

###### Events & Promotions in November
PrevNext
SuMoTuWeThFrSa
28293031123
45678910
11121314151617
18192021222324
2526272829301
Open Detailed Calendar
• ### Essential GMAT Time-Management Hacks

November 14, 2018

November 14, 2018

07:00 PM PST

08:00 PM PST

Join the webinar and learn time-management tactics that will guarantee you answer all questions, in all sections, on time. Save your spot today! Nov. 14th at 7 PM PST
• ### $450 Tuition Credit & Official CAT Packs FREE November 15, 2018 November 15, 2018 10:00 PM MST 11:00 PM MST EMPOWERgmat is giving away the complete Official GMAT Exam Pack collection worth$100 with the 3 Month Pack ($299) # Suppose f(x)=ax^4+bx^2+1, where a and b are constants. If f(3)=9, what  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics Author Message TAGS: ### Hide Tags Math Revolution GMAT Instructor Joined: 16 Aug 2015 Posts: 6499 GMAT 1: 760 Q51 V42 GPA: 3.82 Suppose f(x)=ax^4+bx^2+1, where a and b are constants. If f(3)=9, what [#permalink] ### Show Tags 24 Oct 2018, 00:19 00:00 Difficulty: 15% (low) Question Stats: 88% (00:43) correct 13% (01:02) wrong based on 24 sessions ### HideShow timer Statistics [Math Revolution GMAT math practice question] Suppose $$f(x)=ax^4+bx^2+1$$, where $$a$$ and $$b$$ are constants. If $$f(3)=9$$, what is the value of $$f(-3)$$ ? $$A. -9$$ $$B. -3$$ $$C. 0$$ $$D. 3$$ $$E. 9$$ _________________ 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"

Director
Status: Learning stage
Joined: 01 Oct 2017
Posts: 930
WE: Supply Chain Management (Energy and Utilities)
Re: Suppose f(x)=ax^4+bx^2+1, where a and b are constants. If f(3)=9, what  [#permalink]

### Show Tags

24 Oct 2018, 01:15
MathRevolution wrote:
[Math Revolution GMAT math practice question]

Suppose $$f(x)=ax^4+bx^2+1$$, where $$a$$ and $$b$$ are constants. If $$f(3)=9$$, what is the value of $$f(-3)$$ ?

$$A. -9$$
$$B. -3$$
$$C. 0$$
$$D. 3$$
$$E. 9$$

Notice that the given polynomial function f(x) contains even exponents of x, i.e, $$x^4$$ and $$x^2$$. Hence f(x) is an even function.
Therefore f(-x)=f(x)

Hence, f(-3)=f(3)=9.

Ans. (E)
_________________

Regards,

PKN

Rise above the storm, you will find the sunshine

Math Revolution GMAT Instructor
Joined: 16 Aug 2015
Posts: 6499
GMAT 1: 760 Q51 V42
GPA: 3.82
Re: Suppose f(x)=ax^4+bx^2+1, where a and b are constants. If f(3)=9, what  [#permalink]

### Show Tags

25 Oct 2018, 23:54
1
=>

$$f(3) =a(3)^4 + b(3)^2 + 1 = 81a + 9b + 1 = 9$$
$$f(-3) =a(-3)^4 + b(-3)^2 + 1 = 81a + 9b + 1 = f(3) = 9$$

_________________

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"

Re: Suppose f(x)=ax^4+bx^2+1, where a and b are constants. If f(3)=9, what &nbs [#permalink] 25 Oct 2018, 23:54
Display posts from previous: Sort by