K^2+k-2>0
(K-1)(k+2)>0
so eithere K>1 & K>-2
Or k<1 & k<-2
Plot the options on Number line
I) no suff
II) no suff
I+II = Suff Ans C.
K^2 + K -2 >0
This topic has expert replies
Source: Beat The GMAT — Data Sufficiency |
-
luckylucky
- Junior | Next Rank: 30 Posts
- Posts: 17
- Joined: Mon Dec 01, 2008 8:37 pm
Is K^2 + K-2 >0 ?
1) k<1
2) k>-1
The above equation can be deduced to (k + 2) ( k -1) > 0
This is satisfied by k > -2 and K > 1 i.e k > 1
1) k < 1
plug in 0
-2 > 0 not satisfied
plug in -10
100 - 10 - 2 > 0
88 > 0 satisfies
Hence A alone is not sufficient
2) k > -1
plug in 0
-2 > 0 doesnt satisfy
plug in 10
100 + 10 - 2 > 0
108 > 0 satisfies
Hence B alone is not sufficient
Combinig both A and B
-1 < k < 1
plug in 0
- 2 > 0 doesnt satisfy
plug in 0.9
0.81 + 0.9 - 2 > 0
-1.1 > 0 doesnt satisfy
We can be able to answer the question only when both the statements are combined
Hence C
1) k<1
2) k>-1
The above equation can be deduced to (k + 2) ( k -1) > 0
This is satisfied by k > -2 and K > 1 i.e k > 1
1) k < 1
plug in 0
-2 > 0 not satisfied
plug in -10
100 - 10 - 2 > 0
88 > 0 satisfies
Hence A alone is not sufficient
2) k > -1
plug in 0
-2 > 0 doesnt satisfy
plug in 10
100 + 10 - 2 > 0
108 > 0 satisfies
Hence B alone is not sufficient
Combinig both A and B
-1 < k < 1
plug in 0
- 2 > 0 doesnt satisfy
plug in 0.9
0.81 + 0.9 - 2 > 0
-1.1 > 0 doesnt satisfy
We can be able to answer the question only when both the statements are combined
Hence C
-
mjjking
- Master | Next Rank: 500 Posts
- Posts: 353
- Joined: Sat Jan 20, 2007 1:29 am
- Location: Italy
- Thanked: 7 times
- GMAT Score:720
agrre with C. when -1<k<1 we can answer to the answer with a definite "no", hence suff.
Beat The GMAT - 1st priority
Enter a top MBA program - 2nd priority
Loving my wife: MOST IMPORTANT OF ALL!
REAL THING 1 (AUG 2007): 680 (Q43, V40)
REAL THING 2 (APR 2009): 720 (Q47, V41)
Enter a top MBA program - 2nd priority
Loving my wife: MOST IMPORTANT OF ALL!
REAL THING 1 (AUG 2007): 680 (Q43, V40)
REAL THING 2 (APR 2009): 720 (Q47, V41)
