GMAT PREP DS Question

This topic has expert replies
Newbie | Next Rank: 10 Posts
Posts: 2
Joined: Tue Jan 08, 2008 11:19 am

GMAT PREP DS Question

by nikunj » Thu Dec 11, 2008 6:43 am
In the xy-plane, does the line with equation y = 3x + 2 contain the point (r,s) ?

(1) (3r + 2 - s) (4r + 9 - s) = 0

(2) (4r - 6 - s) (3r + 2 - s) = 0


from the equation y = 3x + 2, we get to know that SLOPE = 3. so point (r,s) should also have the same slope.

By solving statement 1, we get
s = 3r + 2 and s = 4r + 9
so, the slope = 3 or 4

By solving statement 2, we get
s = 4r - 6 and s = 3r + 2
so, the slope = 4 or 3

Now considering both statements, we get SLOPE = 3 or 4. so i selected "E". But the OA is "C"

Please help to clarify the same.

Thanks & Regards
Nikunj

Newbie | Next Rank: 10 Posts
Posts: 4
Joined: Tue Oct 21, 2008 8:15 pm

by jahnaviyeruva » Thu Dec 11, 2008 8:28 am
The question asks if y = 3x + 2 contain the point (r,s)
=> is S=3r+2??

From option 1 we get S=3r+2 or S=4r+9
So option 1 is insff

From option 2 we get S=4r-6 or S=3r+2
So option 2 is insuff

Considering both we can conclude that S=3r+2
Hence the answer is C.....Hope this clarifies your doubt :)

Newbie | Next Rank: 10 Posts
Posts: 2
Joined: Tue Jan 08, 2008 11:19 am

by nikunj » Thu Dec 11, 2008 9:42 pm
Thanks jahnaviyeruva. Now I got it.

User avatar
Legendary Member
Posts: 546
Joined: Sun Nov 16, 2008 11:00 pm
Location: New Delhi , India
Thanked: 13 times

by ronniecoleman » Thu Dec 11, 2008 10:08 pm
IMO C
Admission champion, Hauz khaz
011-27565856

Senior | Next Rank: 100 Posts
Posts: 35
Joined: Wed Oct 29, 2008 5:14 am

by coffee5251 » Wed Jan 07, 2009 7:42 pm
jahnaviyeruva wrote:
Considering both we can conclude that S=3r+2
Hence the answer is C.....Hope this clarifies your doubt :)
even if we don't now what the values of S and R is the answer C because we hypothetically could use algebra to solve for them (not that we would)?

Or is there another reason why the two taken together are suff?