Quote:
If \(-1<x<0\), what is the median of these six numbers listed below
\(\frac{1}{x^3}\), \(\frac{1}{x^2}\), \(\frac{1}{x}\), \(x\), \(x^2\), \(x^3\)
(A) \(\frac{1}{x}\)
(B) \(x^2\)
(C) \(\frac{x^2(x+1)}{2}\)
(D) \(\frac{x(x^2+1)}{2}\)
(E) \(\frac{x^2}{2x}\)
Now x is a fraction between 0 and -1..
First way A quick look at the choice will give you the answer..
Six numbers out of which terms with EVEN power will be positive and rest 4 negative,
so Median will be average of two negative numbers..
A) Median is average of two different numbers,
so median will NOT be a part of these 7 numbers. Eliminate the choices that contain any of these 7 numbers.. A and B out
B)
Choice will NOT be positive..\(x^2(x+1)\) will be positive.. Eliminate C
C) E turns out to be \(\frac{x}{2}\) or \(\frac{1}{2}\) of x, but
it is supposed to be half of two different numbers of the set..Eliminate
D Is the answer
Second wayProperties of negative fractions>-1....
For median, we look for two center values out of 6 numberseven power will be the
greatest numbers, so \(x^2\) and \(\frac{1}{x^2}\) are out..
Since x is fraction and negative, \(\frac{1}{x}\) and \(\frac{1}{x^3}\)
will be smallest..
Remaining two numbers \(x^3\) and x..
Average of these =\(\frac{(x^3+x)}{2}.\)...
D
Third wayTake value as -1/2 and check..
May be better to take fractions than to take decimals