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

Redeem
TTP OnDemand GMAT Video Course
Featured Course

Target Test Prep GMAT OnDemand

Scott Woodbury-Stewart’s private virtual classroom — 400 hours of master-class video lessons for the GMAT Focus Edition.

  • 715+ score guarantee — highest in the industry (99th percentile)
  • 52 chapters · 1,500+ lessons · 4,000+ practice questions
  • 400 hours of video · 1,500+ instructor-led HD smartboard lessons
  • 300,000+ students accepted to Harvard, Stanford, Wharton, Booth & Sloan & more
  • 24/7 live support + weekly Zoom office hours with GMAT instructors
  • TTP AI Assist — 24/7 AI-powered virtual tutor for instant help
  • 1,200+ flashcards + AI-powered study assistant & daily calendar
  • OnDemand, LiveTeach & GMAT Bootcamp formats available
  • Also: GRE, SAT Math & Executive Assessment courses
  • MBA Admissions Consulting now available
  • 🏆 2025 EdTech Breakthrough Award: Test Prep Solution Provider of the Year
  • 200,000+ students served
  • 5-day free trial — $0 to start, no auto-billing, cancel anytime
★★★★★ 5.0 (559 reviews)
130-pt guarantee
$0 to start then $127/mo
Start Free 5-Day Trial Read 559 Reviews →

Evaluating radical expressions - Please Help ASAP

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Newbie | Next Rank: 10 Posts
Posts: 2
Joined: Wed Nov 11, 2009 9:06 am
by postroske » Tue Nov 24, 2009 8:16 pm
I am taking the GMAT tomorrow and felt prepared until I saw this question on the GMAT's software practice test. I can not figure out how to properly evaluate this expression.

(sqrt(9+sqrt(80)) + sqrt(9-sqrt(80)))^2

the ^2 indicates that the entire expression is to the second power or squared. I can not figure it out and would like to know before i go in tomorrow. If you can, please explain method.

Thanks!
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Problem Solving |
User avatar
Master | Next Rank: 500 Posts
Posts: 172
Joined: Wed Jul 09, 2008 3:35 amFollowed by: 1 member
Thanked: 3 times
GMAT Score:610

by karthikgmat » Tue Nov 24, 2009 10:59 pm
9 can be written as sqrt(5)^2+sqrt(4)^2 and sqrt(80) can be written as sqrt( 4*4*5)
it is square of (a+b)

so the first term is sqrt(5)+2
second term is sqrt(5) -2
adding two we get 2 sqrt(5)

finally squaring that 4*5 =20

..is it ok?
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Junior | Next Rank: 30 Posts
Posts: 12
Joined: Thu Aug 27, 2009 6:05 am
Thanked: 5 times
GMAT Score:640

by nikilnikil » Wed Nov 25, 2009 12:47 am
this expression is of the form

(a+b)^2 = a^2+b^2+2*a*b

sqrt(9+sqrt(80)) ^2 + sqrt(9-sqrt(80))^2 + 2* sqrt((9+sqrt(80))*(9-sqrt(80))

= 9+sqrt(80) + 9 - sqrt(80) + 2 * (81-80) [because (a+b)(a-b) = a^2 -b^2]
=9+9+2 = 20

~Nik
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Newbie | Next Rank: 10 Posts
Posts: 2
Joined: Wed Nov 11, 2009 9:06 am

by postroske » Wed Nov 25, 2009 6:27 am
thank you both. great explanation!!
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1