Live GMAT classes with Target Test Prep start Nov 21 and Nov 22. First class free.

See classes
Target Test Prep · GMAT

Choose how you want to prepare

Learn live with an expert or move at your own pace. Every option includes the complete TTP study system.

Newsweek Readers’ Choice Awards 2026 winner: Target Test Prep, #1 Test Prep

Target Test Prep was voted #1 Best Test Prep in the 2026 Newsweek Readers’ Choice™ Awards.

★★★★★5.0563 reviews
GMATLiveTeachStarts Nov 22
Josh Braslow, Target Test Prep GMAT expert
LIVE ONLINE CLASSES

Get Ready for GMAT Test Day Faster with Live Online Classes

with Josh Braslow, 20+ years in test prep

Nov 22 · Josh Braslow
Sun · 9:30 AM to 12:30 PM ET
Included
40 hours of live online classes + 6 months of TTP OnDemand
  • Attend the first class for free
  • Every class is recorded, so you never fall behind
View classes & enroll
Limited seats availableTarget Test Prep
EALiveTeachOnDemandStart anytime
EXECUTIVE ASSESSMENT

Target Test Prep EA OnDemand

Self-paced EA prep. Study on your schedule.

EXECUTIVE ASSESSMENT

with

165+ EA score guarantee
$05-day trial no automatic billing
Schedule
Included
40 hours of live online classes plus six months of access to the complete TTP EA OnDemand course.
  • 165+ EA Score Guarantee
  • 4,100+ Quant, Verbal, and Integrated Reasoning practice questions
  • 400+ hours of in-depth video lessons
  • 3,000+ step-by-step video solutions
View EA class & enroll Start free 5-day trial
Limited cohort · enrollment openTrial includes full course accessTarget Test Prep
GMATOnDemandStart anytime
SELF-PACED MASTERCLASS

Target Test Prep GMAT OnDemand

Complete access from day one. Study on your schedule.

715+ score guarantee
$0to start then $127/mo
  • Personalized study plan and analytics
  • Thousands of lessons and practice questions
Start free 5-day trial
Read 563 reviewsTarget Test Prep

Suppose f(x)=ax^4+bx^2+1, where a and b are constants. If f(

Expert replies
Post new topic Post Reply
Subscribe topic
Previous Topic Next Topic
User avatar
Elite Legendary Member
Posts: 3991
Joined: Fri Jul 24, 2015 2:28 amFollowed by: 37 members
Location: Las Vegas, USA
Thanked: 19 times
by Max@Math Revolution » Wed Oct 24, 2018 12:09 am
Timer
00:00
Your answer
Difficulty–

right wrong

Pick an answer to see how members did

[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
Top
Join the discussion
Source: — Problem Solving |
User avatar
GMAT Instructor
Posts: 1449
Joined: Sat Oct 09, 2010 2:16 pmFollowed by: 33 members
Thanked: 59 times

by fskilnik@GMATH » Wed Oct 24, 2018 2:42 am
Max@Math Revolution 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
$$f\left( x \right) = a \cdot {x^4} + b \cdot {x^2} + 1\,\,\,\,\,\,\left( {a,b\,\,{\rm{conts}}} \right)$$
$$? = f\left( { - 3} \right) = a \cdot {\left( { - 3} \right)^4} + b \cdot {\left( { - 3} \right)^2} + 1 = a \cdot {3^4} + b \cdot {3^2} + 1$$
$$9 = f\left( 3 \right) = a \cdot {3^4} + b \cdot {3^2} + 1\,\,\,\,\, \Rightarrow \,\,\,\,\,? = 9$$

This solution follows the notations and rationale taught in the GMATH method.

Regards,
Fabio.
Fabio Skilnik :: GMATH method creator ( Math for the GMAT)
English-speakers :: https://www.gmath.net
Portuguese-speakers :: https://www.gmath.com.br
Top
Join the discussion

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 8246
Joined: Sat Apr 25, 2015 10:56 amFollowed by: 29 members
Location: Los Angeles, CA
Thanked: 43 times

by Scott@TargetTestPrep » Thu Oct 25, 2018 4:57 pm
Max@Math Revolution 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
The notation f(3) = 9 means that when x = 3, then y = 9. We are asked to find the value of the function when x = -3.

Before you try to plug -3 into the function ax^4+bx^2+1 and then try to do the lengthy and confusing arithmetic, notice that 3^4 equals (-3)^4, and 3^2 equals (-3)^2. So, no matter if x = 3 OR if x = -3, the answer to the function will be the same for f(3) and for f(-3), since the exponents are even numbers. Thus, f(3) = f(-3) = 9. No arithmetic is necessary!.

Answer: E

Scott Woodbury-Stewart
Founder and CEO
[email protected]

Image

See why Target Test Prep is rated 5 out of 5 stars on BEAT the GMAT. Read our reviews

ImageImage
Top
Join the discussion
User avatar
Elite Legendary Member
Posts: 3991
Joined: Fri Jul 24, 2015 2:28 amFollowed by: 37 members
Location: Las Vegas, USA
Thanked: 19 times

by Max@Math Revolution » Thu Oct 25, 2018 11:45 pm
=>

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

Therefore, the answer is E.
Answer: E
Top
Join the discussion