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 →

factor of t..then k=

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
User avatar
Newbie | Next Rank: 10 Posts
Posts: 3
Joined: Wed Jun 23, 2010 1:44 pm
by mknmknmkn » Fri Sep 17, 2010 5:44 am
Problem 55 in GMAT Quantitative Review, I still don't understand after looking at the explanation.

If (T-8) is a factor of T^2-KT-48, then K=

(A) 16
(B) 12
(C) 2
(D) 6
(E) 14

The correct answer is C. According to the book, but I don't understand. Can someone shed some light on this for me?
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Problem Solving |
User avatar
Legendary Member
Posts: 1893
Joined: Sun May 30, 2010 11:48 pmFollowed by: 7 members
Thanked: 215 times

by kvcpk » Fri Sep 17, 2010 6:43 am
If (T-8) is a factor of T^2-KT-48, then K=?

If T-8 is a factor, it means that 8 is a root of the eqtn.

Remember this.
in the eqtn: ax^2+bx+c, sum of the roots = -b/a and product of roots = c/a

now,
in the eqtn, T^2-KT-48, a=1, b =-k, c= -48

We know that one root is 8. Let the other root be P
P+8 = -b/a = k
P(8) = c/a = -48
P=-6

Substitute in the above:
-6+8 = k

Hence k=2.

Hope this helps!!
"Once you start working on something,
don't be afraid of failure and don't abandon it.
People who work sincerely are the happiest."
Chanakya quotes (Indian politician, strategist and writer, 350 BC-275BC)
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Master | Next Rank: 500 Posts
Posts: 385
Joined: Sun Jul 12, 2009 10:16 pmFollowed by: 2 members
Thanked: 29 times
GMAT Score:710

by debmalya_dutta » Fri Sep 17, 2010 7:26 am
mknmknmkn wrote:Problem 55 in GMAT Quantitative Review, I still don't understand after looking at the explanation.

If (T-8) is a factor of T^2-KT-48, then K=

(A) 16
(B) 12
(C) 2
(D) 6
(E) 14

The correct answer is C. According to the book, but I don't understand. Can someone shed some light on this for me?
Since T-8 is a factor , it means that when T=8 , then the equation T^2-KT-48 = 0
So, substitute value of T as 8 in the equation
K = 2

What Praveen has identified in his note is something good to know .
@Deb
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Newbie | Next Rank: 10 Posts
Posts: 3
Joined: Wed Jun 23, 2010 1:44 pm

by mknmknmkn » Sat Sep 18, 2010 7:54 am
It was so obvious but I didn't get it. Now I got it, thanks!

Level up!
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1