paddy41 wrote:
If x and y are negative and \(x^4-y^4<0\) which of the following must be true?
I: \(x<y\)
II: \(xy<y^2\)
III: \((x+y)^2<(x-y)^2\)
A.) I only
B.) II only
C.) III only
D.) I & II
E.) II & III
From question stem, We can organize exmaples
Let x = -1 & y = -2
Let x = \(\frac{-1}{4}\) & y = \(\frac{-1}{2}\)
Let x = \(\frac{-1}{2}\) & y = -1
I: \(x<y\)........From examples above..........
NOT TrueII: \(xy<y^2\)....\(xy-y^2<0\).......y<0 & x>y........From examples above........
TrueIII: \((x+y)^2<(x-y)^2\)..........Take first example to DISPROVE........
NOT TrueAnswer: B