1) Is √(x-3)² = 3-x?
1) x not equal to 3
2) –x|x| >0
Anyone help me with this one?
Thanks!
5-Day Free Trial
5-day free, full-access trial TTP
Available with Beat the GMAT members only code
MORE DETAILS
GMATprep: absolute value - I scare the most
This topic has expert replies
-
tohellandback
- Legendary Member
- Posts: 752
- Joined: Sun May 17, 2009 11:04 pm
- Location: Tokyo
- Thanked: 81 times
- GMAT Score:680
IMO B
√(x-3)² = x-3 when x-3>=0
=3-x when x-3<0
A) not sufficient
B)–x|x|=0, so x must be negative
B is suffiecient
√(x-3)² = x-3 when x-3>=0
=3-x when x-3<0
A) not sufficient
B)–x|x|=0, so x must be negative
B is suffiecient
The powers of two are bloody impolite!!
-
rah_pandey
- Master | Next Rank: 500 Posts
- Posts: 122
- Joined: Fri May 22, 2009 10:38 pm
- Thanked: 8 times
- GMAT Score:700
x not equal to 3 => answer is not zero and so a conscious decision has to be made to either put answer as x-3 or 3-x
√(x-3)² = +/-(x-3)
in second condition it is given
-x|x|>0
since |x|>0 always
therefore -x>0
=> x<0
now
let x=-k where k>0
√(-k-3)² =k+3 (here we are not taking -ve value as by convention √X=> positive root.
=3-x (replace k by -x)
B is sufficient
√(x-3)² = +/-(x-3)
in second condition it is given
-x|x|>0
since |x|>0 always
therefore -x>0
=> x<0
now
let x=-k where k>0
√(-k-3)² =k+3 (here we are not taking -ve value as by convention √X=> positive root.
=3-x (replace k by -x)
B is sufficient
