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

Redeem

quad

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Source: — Problem Solving |
Senior | Next Rank: 100 Posts
Posts: 85
Joined: Sat Aug 15, 2009 4:36 am
Thanked: 19 times

by gmatjedi » Fri May 28, 2010 3:26 am
equation needs to be in form of (x-a)(x-b)

d: (x-4)(x-2)
Top
User avatar
Legendary Member
Posts: 1460
Joined: Tue Dec 29, 2009 1:28 am
Thanked: 135 times
Followed by:7 members

by selango » Fri May 28, 2010 3:29 am
Substitute options in the equation,

x2-6x+k=0

Only 9 and 8 satisfies the condition.

From this only 8 has 2 distinct roots

So 8 is answer
Top
User avatar
Master | Next Rank: 500 Posts
Posts: 362
Joined: Fri Oct 02, 2009 4:18 am
Thanked: 26 times
Followed by:1 members

by indiantiger » Fri May 28, 2010 3:33 am
Here is my brute force method, replace the value of k by answer choices:
A. 9 => x^2 - 6x + 9=> (x-3)^2 NO
B. 7 => x^2 - 6x + 7 => NO
C. 3 => x^2-6x +3 => NO
D. 8 => x^2 -6x + 8 => x^2 -4x-2x+8 => (x-4)(x-2) {ANSWER}
E. 12 => x^2 -6x +12 =>NO
"Single Malt is better than Blended"
Top
Legendary Member
Posts: 576
Joined: Sat Mar 13, 2010 8:31 pm
Thanked: 97 times
Followed by:1 members

by liferocks » Fri May 28, 2010 4:20 am
for x2 - 6x + k = 0 have real and distinct root
36-4k>0
or 9>k
so highest integral value of k=8

Ans option D
"If you don't know where you are going, any road will get you there."
Lewis Carroll
Top
User avatar
Master | Next Rank: 500 Posts
Posts: 362
Joined: Fri Oct 02, 2009 4:18 am
Thanked: 26 times
Followed by:1 members

by indiantiger » Fri May 28, 2010 2:44 pm
@LifeRocks

awesome solution :), never thought of using b^2 - 4ac
"Single Malt is better than Blended"
Top
Post new topic Post Reply
• Page 1 of 1