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Source: — Problem Solving |

by killer1387 » Fri Mar 23, 2012 11:15 pm
romitvsingh wrote:the LCM of polynomials (36x^2-49) and (6x^2-25x+21)is

a (x-3)

b (x-3)^2 (6x-7)

c (x-3) (6x-7) (6x+7)

d none of these
(36x^2-49) = (6x-7)*(6x+7), and
(6x^2-25x+21)= (6x-7)*(x-3)

LCM=(X-3)*(6X+7)*(6X-7)

HENCE C
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by [email protected] » Sun Apr 01, 2012 3:30 am
Well bro killer1387 you have committed a minor mistake...


The answer should be D and not C. the reason is that see the factors once...\

the factors of 6x^2 - 9x - 14x + 21

= 3x (2x - 3) - 7 (2x - 3)

= (3x - 7) (2x - 3)

hence the factors are (3x - 7) (2x - 3) (6x - 7) (6x + 7)


none of the options A , B or C are the above hence D.

I am sure of this... please see this and let me know


By the way what is the OA romitvsingh...
IT IS TIME TO BEAT THE GMAT

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by Pharo » Sun Apr 01, 2012 3:39 am
[email protected] wrote:Well bro killer1387 you have committed a minor mistake...


The answer should be D and not C. the reason is that see the factors once...\

the factors of 6x^2 - 9x - 14x + 21

= 3x (2x - 3) - 7 (2x - 3)

= (3x - 7) (2x - 3)

hence the factors are (3x - 7) (2x - 3) (6x - 7) (6x + 7)


none of the options A , B or C are the above hence D.

I am sure of this... please see this and let me know


By the way what is the OA romitvsingh...
Nope, you made a mistake: 9 + 14 = 23; not 25 :)

The answer is C.
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by Anurag@Gurome » Sun Apr 01, 2012 8:53 pm
romitvsingh wrote:the LCM of polynomials (36x^2-49) and (6x^2-25x+21)is

a (x-3)

b (x-3)^2 (6x-7)

c (x-3) (6x-7) (6x+7)

d none of these
(36x^2 - 49) = (6x + 7)(6x - 7)
(6x^2 - 25x + 21) = 6x^2 - 18x - 7x + 21 = 6x(x - 3) - 7(x - 3) = (x - 3)(6x - 7)

Therefore, LCM of (36x^2 - 49) and (6x^2 - 25x + 21) = [spoiler](x - 3)(6x + 7)(6x - 7) [/spoiler]

The correct answer is C.
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by Anurag@Gurome » Sun Apr 01, 2012 8:53 pm
Delete
Last edited by Anurag@Gurome on Sun Apr 01, 2012 8:54 pm, edited 1 time in total.
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by Anurag@Gurome » Sun Apr 01, 2012 8:54 pm
Delete.
Anurag Mairal, Ph.D., MBA
GMAT Expert, Admissions and Career Guidance
Gurome, Inc.
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by [email protected] » Mon Apr 02, 2012 10:40 pm
yes thank you guyzzz a silly mistake from my side... I am sorry.. I got my mistake...
IT IS TIME TO BEAT THE GMAT

LEARNING, APPLICATION AND TIMING IS THE FACT OF GMAT AND LIFE AS WELL... KEEP PLAYING!!!

Whenever you feel that my post really helped you to learn something new, please press on the 'THANK' button.
Join the discussion