Last visit was: 20 Nov 2025, 05:12 It is currently 20 Nov 2025, 05:12
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.
Close
Request Expert Reply
Confirm Cancel
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 20 Nov 2025
Posts: 105,414
Own Kudos:
Given Kudos: 99,987
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 105,414
Kudos: 778,490
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
Abinash34
Joined: 18 Nov 2021
Last visit: 19 Nov 2025
Posts: 8
Own Kudos:
3
 [1]
Given Kudos: 41
Location: India
Concentration: General Management, Strategy
Posts: 8
Kudos: 3
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 20 Nov 2025
Posts: 105,414
Own Kudos:
Given Kudos: 99,987
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 105,414
Kudos: 778,490
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
findingmyself
Joined: 06 Apr 2025
Last visit: 19 Nov 2025
Posts: 230
Own Kudos:
Given Kudos: 57
Posts: 230
Kudos: 157
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Since first equation has equal roots, Let us call it "a",
Since first equation and second equation has one root in common, lets call the roots of second equation as "a" (common) and "b"
Product of roots of a quadratic equation in the forms ax^2+bx+c is (c/a)
Sum of roots of a quadratic equation in the forms ax^2+bx+c is (-b/a)

Thus a^2=(-n) from the first equation
ab=-15

a+a=-m
a+b=-m

2a=a+b
a=b

Substituting in ab=-15, a^2=-15

Since a^2=(-n)-----> n=15

Where did I go wrong?
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 20 Nov 2025
Posts: 105,414
Own Kudos:
Given Kudos: 99,987
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 105,414
Kudos: 778,490
Kudos
Add Kudos
Bookmarks
Bookmark this Post
findingmyself
Since first equation has equal roots, Let us call it "a",
Since first equation and second equation has one root in common, lets call the roots of second equation as "a" (common) and "b"
Product of roots of a quadratic equation in the forms ax^2+bx+c is (c/a)
Sum of roots of a quadratic equation in the forms ax^2+bx+c is (-b/a)

Thus a^2=(-n) from the first equation
ab=-15

a+a=-m
a+b=-m

2a=a+b
a=b

Substituting in ab=-15, a^2=-15

Since a^2=(-n)-----> n=15

Where did I go wrong?

Your mistake is assuming the two equations share a common root. The question never says that.
User avatar
Goshim
Joined: 10 Apr 2024
Last visit: 02 Oct 2025
Posts: 2
Given Kudos: 2
Posts: 2
Kudos: 0
Kudos
Add Kudos
Bookmarks
Bookmark this Post
I like the solution - it’s helpful.
User avatar
Goshim
Joined: 10 Apr 2024
Last visit: 02 Oct 2025
Posts: 2
Given Kudos: 2
Posts: 2
Kudos: 0
Kudos
Add Kudos
Bookmarks
Bookmark this Post
I like the solution - it’s helpful.
User avatar
Mahi_M
Joined: 06 May 2023
Last visit: 17 Nov 2025
Posts: 1
Given Kudos: 1
Location: India
GMAT Focus 1: 645 Q79 V86 DI80
GPA: 4
WE:Brand Management (Advertising and PR)
Products:
GMAT Focus 1: 645 Q79 V86 DI80
Posts: 1
Kudos: 0
Kudos
Add Kudos
Bookmarks
Bookmark this Post
I did not quite understand the solution. where does k squared come from?
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 20 Nov 2025
Posts: 105,414
Own Kudos:
Given Kudos: 99,987
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 105,414
Kudos: 778,490
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Mahi_M
I did not quite understand the solution. where does k squared come from?

Could you please tell me where do you see k^2 in the solution? There are two different solutions given here. Which one are you referring to? Also, have you had a chance to review other solutions given in the thread?
User avatar
enidaddams
Joined: 05 Sep 2025
Last visit: 17 Nov 2025
Posts: 6
Given Kudos: 29
Products:
Posts: 6
Kudos: 0
Kudos
Add Kudos
Bookmarks
Bookmark this Post
I like the solution - it’s helpful.
User avatar
tuyetvan1796
Joined: 11 Jun 2025
Last visit: 19 Nov 2025
Posts: 4
Products:
Posts: 4
Kudos: 0
Kudos
Add Kudos
Bookmarks
Bookmark this Post
I like the solution - it’s helpful.
User avatar
possimusquidem
Joined: 01 Sep 2025
Last visit: 19 Nov 2025
Posts: 1
Given Kudos: 5
Products:
Posts: 1
Kudos: 0
Kudos
Add Kudos
Bookmarks
Bookmark this Post
I like the solution - it’s helpful.
User avatar
phil2804
Joined: 26 Sep 2025
Last visit: 20 Nov 2025
Posts: 12
Given Kudos: 68
Products:
Posts: 12
Kudos: 0
Kudos
Add Kudos
Bookmarks
Bookmark this Post
I like the solution - it’s helpful.
   1   2 
Moderators:
Math Expert
105414 posts
Founder
42395 posts