queenisabella wrote:can someone please explain the answer explanation to this question? to me, answer B still seems to be right, yet VP is saying D is, and the answer does not make sense to me.
Since Y^4 is
always positive, X^3 must also always be positive.
If X^3 is always positive, then X must be positive. (If X is negative, then X^3 is negative.)
Since X is always positive, and Y^2 is positive (anything squared is positive), then (X)(Y^2) cannot be negative. Positive times positive = positive.
I think where the answer key goes wrong is here: "B could still be true ... (i.e., y=-1/4 and x=-1/5)" ---- should say y=-1/4 and x=
+1/5.
If y=-1/4 and x =-1/5, then the original statement does not hold true. X^3=-1/125 does not > Y^4=1/256.
If y=-1/4 and x=1/5, then the original statement is correct, X^3=1/125 > Y^4=1/256, and statement B is true where -1/4+1/5=-1/20
X
must be positive.
Hope this helps.
