NEW HERE? LEARN MORE
closeclose
Last visit was: 26 Apr 2024, 16:31 It is currently 26 Apr 2024, 16:31
Decision Tracker
My Rewards
New posts
New comers' posts

Close
GMAT Club Daily Prep
Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Go to My Error Log Learn more
Close
Request Expert Reply
Confirm Cancel

Given that m^2 - 2m -15 = 0 and n^2 - 3n - 10 = 0, where m ≠ n, what

SORT BY:
Date
Kudos
Tags:
Find Similar Topics 
Show Tags
Hide Tags
User avatar
L
Bunuel
Math Expert
Joined: 02 Sep 2009
Posts: 92948
Own Kudos [?]: 619239 [0]
Given Kudos: 81609
Send PM
CAT Tests Forum Quiz Mode
Given that m^2 - 2m -15 = 0 and n^2 - 3n - 10 = 0, where m ≠ n, what [#permalink] New post   10 Apr 2018, 22:18
Expert Reply
00:00
A
B
C
D
E

Difficulty:

15% (low)

Question Stats:

80% (01:27) correct 20% (01:50) wrong based on 143 sessions
Hide Show timer Statistics
Given that \(m^2 - 2m -15 = 0\) and \(n^2 - 3n - 10 = 0\), where m ≠ n, what is the product of m and n?

(A) -15
(B) -10
(C) -6
(D) 6
(E) 15
ShowHide Answer
Official Answer
D
User avatar
L
pushpitkc
Senior PS Moderator
Joined: 26 Feb 2016
Posts: 2873
Own Kudos [?]: 5206 [0]
Given Kudos: 47
Location: India
GPA: 3.12
Send PM
Re: Given that m^2 - 2m -15 = 0 and n^2 - 3n - 10 = 0, where m ≠ n, what [#permalink] New post   10 Apr 2018, 23:41
Bunuel wrote:
Given that \(m^2 - 2m -15 = 0\) and \(n^2 - 3n - 10 = 0\), where m ≠ n, what is the product of m and n?

(A) -15
(B) -10
(C) -6
(D) 6
(E) 15



Factorizing the two equations
\(m^2 - 2m -15 = 0\) -> \(m^2 - 5m + 3n -15 = 0\) -> \((m-5)(m+3) = 0\) -> \(m = 5 or -3\)
\(n^2 - 3n - 10 = 0\) -> \(n^2 - 5n + 2n - 10 = 0\) -> \((n-5)(n+2) = 0\) -> \(n = 5 or -2\)

Therefore, the product of m and n such that m≠n is (-3)(-2) = 6(Option D)
avatar
B
linggling
Intern
Intern
Joined: 07 Jul 2017
Posts: 1
Own Kudos [?]: 0 [0]
Given Kudos: 8
Send PM
Re: Given that m^2 - 2m -15 = 0 and n^2 - 3n - 10 = 0, where m ≠ n, what [#permalink] New post   11 Apr 2018, 02:13
Can answer be -10 and -15 also? the question stated that m ≠ n , doesn’t that means m = 5, n = -2 or m = -3, n = 5 also possible?
User avatar
P
push12345
Director
Director
Joined: 02 Oct 2017
Posts: 552
Own Kudos [?]: 481 [0]
Given Kudos: 14
Send PM
Re: Given that m^2 - 2m -15 = 0 and n^2 - 3n - 10 = 0, where m ≠ n, what [#permalink] New post   21 Apr 2018, 06:17
After solving equation we get
m=5 or -3
n=5 or -2

It is written that m is not equal to n
Then options 6,-10 and -15 also fulfill the criteria..
considering choosing the answer answer should be 6
But otherwise options in this question are not correct.

Posted from my mobile device
User avatar
D
KSBGC
VP
VP
Joined: 31 Oct 2013
Posts: 1260
Own Kudos [?]: 1155 [0]
Given Kudos: 635
Concentration: Accounting, Finance
GPA: 3.68
WE:Analyst (Accounting)
Send PM
Given that m^2 - 2m -15 = 0 and n^2 - 3n - 10 = 0, where m ≠ n, what [#permalink] New post   21 Apr 2018, 17:26
Bunuel wrote:
Given that \(m^2 - 2m -15 = 0\) and \(n^2 - 3n - 10 = 0\), where m ≠ n, what is the product of m and n?

(A) -15
(B) -10
(C) -6
(D) 6
(E) 15


It's given that m is not equal to n.

\(m^2-2m-15=0\)

\(m^2 - 5m + 3m - 15 =0\)

m(m-5) + 3(m-5) = 0

(m-5)(m+3)=0

So, the value of m = 5 or -3.

\(n^2 - 3n - 10 = 0\)

\(n^2 - 5n + 2n -10=0\)

(n-5) (n+2) = 0.

So the value of n = 5 or -2

Note: we know m and n can't be equal as per the direction of the question.

Thus the value of mn will be (-3) (-2) = 6

The correct answer is D.
User avatar
L
stne
SVP
SVP
Joined: 27 May 2012
Posts: 1680
Own Kudos [?]: 1424 [0]
Given Kudos: 632
Send PM
Re: Given that m^2 - 2m -15 = 0 and n^2 - 3n - 10 = 0, where m ≠ n, what [#permalink] New post   23 Aug 2018, 05:27
linggling wrote:
Can answer be -10 and -15 also? the question stated that m ≠ n , doesn’t that means m = 5, n = -2 or m = -3, n = 5 also possible?



Absolutely you are correct , on solving for m we get m =5 or m=-3
on solving for n we get n =5 or n =-2
now we know that m \(\neq\) n , hence m and n cannot both be 5, the following pairs of (m n) are possible
(-3 5) (-3,-2) (5, -2) hence product of m and n can be -15, 6, -10 all of these are present in the options .

Please let me know if I am missing anything. Thanks.
GMAT Club Bot
gmatclubot
Re: Given that m^2 - 2m -15 = 0 and n^2 - 3n - 10 = 0, where m ≠ n, what [#permalink]
23 Aug 2018, 05:27
Moderators:
Bunuel
Math Expert
92948 posts
yashikaaggarwal
Senior Moderator - Masters Forum
3137 posts

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne
Main navigation
GMAT Resources
Partners
MBA Resources
www.gmac.com|www.mba.com | | GMAT Club Rules | Terms and Conditions