practice question 55

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

Oxana: Junior | Next Rank: 30 Posts; Posts: 18; Joined: Sun Jul 27, 2008 8:59 am; Thanked: 1 times

by Oxana » Fri Aug 29, 2008 3:57 pm

if (t- 8 ) is a factor of (t^2)- kt-48
then k =

16
12
2
6
14

ans is C

Source: Beat The GMAT — Problem Solving | Fri Aug 29, 2008 3:57 pm

niraj_a: Legendary Member; Posts: 708; Joined: Sun Jun 01, 2008 4:59 am; Location: USA; Thanked: 13 times; Followed by:1 members

by niraj_a » Fri Aug 29, 2008 4:07 pm

try substituting 8 for t in the given equation, and then solve for k.

4meonly: Legendary Member; Posts: 891; Joined: Sat Aug 16, 2008 4:21 am; Thanked: 27 times; Followed by:1 members; GMAT Score:660(

by 4meonly » Mon Sep 01, 2008 12:41 am

(t^2)- kt-48 = (t+6)(t-8 )
because we know that (t-8 ) is a factor of (t^2)- kt-48
solving (t+6)(t-8 ) = (t^2)-8t+6t-48 = t^2-2t-48

k=2

canuckclint: Master | Next Rank: 500 Posts; Posts: 154; Joined: Tue Aug 26, 2008 12:59 pm; Location: Canada; Thanked: 4 times

by canuckclint » Wed Sep 03, 2008 6:09 pm

niraj_a wrote:try substituting 8 for t in the given equation, and then solve for k.

Yes, if 8 is a root.
Then t-8 = 0.
t = 8

• Page 1 of 1