Absolute Value

zagcollins · Posted: Sun Jul 20, 2008 6:27 am Post subject: Absolute Value

If absolute value of n+5= 5, what is the value of n?
(1)n^2 is not equal to 0.
(2)n^2 + 10n = 0

VP_Tatiana · Posted: Sun Jul 20, 2008 9:57 am Post subject:

The problem statement tells us that the absolute value of n+5=5. Thus, we have either that:

a) n+5=5, and n=0 or
b)n+5 = -5, and n=-10

From statement 1, we are told n^2 is not equal to 0. Thus, n is not equal to 0. So, n must be -10. Statement 1 gives us sufficient information to solve for n.

From statement 2, we are told:
n^2 + 10n = 0. We can rewrite this:
n(n+10)=0.
This equation has two solutions: n=0 and n=-10. Thus, statement 2 does not give us a definitive answer for n and is not sufficient.

Since only statement 1 was sufficient, the answer is A.

zagcollins · Posted: Mon Jul 21, 2008 5:02 am Post subject:

good one, tatiana...always fail to rem the negative/positive feature of integers....my bad!