BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

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.

★★★★★5.0559 reviews
GMATLiveTeach 7 seats left
Chris Peckover
NEXT LIVE COHORT

Oct 13 to Jan 7, 2027

with Chris Peckover

Schedule
Tue, Thu · 8:00 to 10:00 PM ET
Included
40 live hours + 6 months of GMAT OnDemand
  • Live instruction and real-time questions
  • Class recordings and assigned practice
View class & enroll
Limited cohort · enrollment openTarget Test Prep
EALiveTeach 5 seats left
Logan Thompson
EXECUTIVE ASSESSMENT

Sep 6 to Dec 6, 2026

with Logan Thompson

Schedule
Sun · 9:30 AM to 12:30 PM ET
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
Limited cohort · enrollment openTarget Test Prep
GMATOnDemand Start 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 559 reviewsTarget Test Prep

Compare the format, schedule, and included access before enrolling. Prices and seat counts shown reflect the supplied offer details.

Need help with this problem

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Source: — Problem Solving |
User avatar
Legendary Member
Posts: 1239
Joined: Tue Apr 26, 2011 6:25 amFollowed by: 26 members
Thanked: 233 times
GMAT Score:680

by sam2304 » Tue Oct 02, 2012 10:31 pm
I assume the sq.root applies to the whole term

sq.rt(x^2 y^3 + 3x^2y^3)
= sq.rt(4x^2y^3)
= (2^2 * x^2 * y^3)^1/2
= 2xy*(y)^1/2, which is the given answer.
Getting defeated is just a temporary notion, giving it up is what makes it permanent.
https://gmatandbeyond.blogspot.in/
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Junior | Next Rank: 30 Posts
Posts: 13
Joined: Sun Aug 26, 2012 5:42 pm

by wayneyau1214 » Wed Oct 03, 2012 4:59 am
√x^2y^3+3x^2y^3
=√4x^2y^3

Why don't the y's add up? I mean, if you add the x's (x^2+3x^2) then should the y's add up too? (y^3+y^3=2y^3)
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 16207
Joined: Mon Dec 08, 2008 6:26 pmFollowed by: 1268 members
Location: Vancouver, BC
Thanked: 5254 times
GMAT Score:770

by Brent@GMATPrepNow » Wed Oct 03, 2012 6:34 am
wayneyau1214 wrote:√x^2y^3+3x^2y^3
This expression could benefit from some extra brackets.
I believe we can write it as:
sqrt[(x^2)(y^3) + (3x^2)(y^3)]
Simplify: sqrt[(4x^2)(y^3)]
Add some color: sqrt[(4x^2)(y^3)]

We have a nice rule that says, sqrt(xy) = [sqrt(x)][sqrt(y)]

When we apply this, we get: [sqrt(4x^2)][sqrt(y^3)]
Simplify to get: [2x][y sqrt(y)]
Rearrange to get: 2xy[sqrt(y)]

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
Image
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
GMAT Instructor
Posts: 15539
Joined: Tue May 25, 2010 12:04 pmFollowed by: 1906 members
Location: New York, NY
Thanked: 13060 times
GMAT Score:790

by GMATGuruNY » Wed Oct 03, 2012 7:47 am
wayneyau1214 wrote:√x^2y^3+3x^2y^3

I got 2xy√2y
but the answer MGMAT gave was 2xy√y
I'm not sure if this is an error they made so I just want to see what you guys got. [/img]
Since the GMAT would provide answer choices, an alternate approach is to plug in values.
If we plug x=1/2 and y=2 into √(x²y³ + 3x²y³), we get:

√( (1/2)²2³ + 3(1/2)²2³ )

= √ ( (1/4)(8) + 3(1/4)8 )

= √ (2 + 6)

= √8

= 2√2.

Now we plug x=1/2 and y=2 into the answers to see which yields our target of 2√2.

Answer choice: 2xy√y
2xy√y = 2(1/2)(2)√2 = 2√2.
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.

As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.

For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Legendary Member
Posts: 1239
Joined: Tue Apr 26, 2011 6:25 amFollowed by: 26 members
Thanked: 233 times
GMAT Score:680

by sam2304 » Wed Oct 03, 2012 11:13 pm
wayneyau1214 wrote:√x^2y^3+3x^2y^3
=√4x^2y^3

Why don't the y's add up? I mean, if you add the x's (x^2+3x^2) then should the y's add up too? (y^3+y^3=2y^3)
x^2y^3 is a single term and 3x^2y^3 is independent term. Its same as adding xy + 2xy = 3xy, you cannot say something like 3x2y, I assume that's what your doubt is.
Getting defeated is just a temporary notion, giving it up is what makes it permanent.
https://gmatandbeyond.blogspot.in/
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Junior | Next Rank: 30 Posts
Posts: 13
Joined: Sun Aug 26, 2012 5:42 pm

by wayneyau1214 » Thu Oct 04, 2012 5:44 am
sam2304 wrote:
x^2y^3 is a single term and 3x^2y^3 is independent term. Its same as adding xy + 2xy = 3xy, you cannot say something like 3x2y, I assume that's what your doubt is.
Got it, thanks!
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1