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Level 3 math question?

RhythmMeleonRhythmMeleon Registered User Posts: 481 Member
edited August 2013 in SAT Preparation
Each of the following inequalities is true for some values of x EXCEPT

a) x< x^2 < x^3
b) x < x^3 < x^2
c) x^2 < x^3 < x
d) x^3 <x <x^2
e) x^3 < x^2 <x

the right answer is D, but I don't get how C isn't the right answer either.
Post edited by RhythmMeleon on

Replies to: Level 3 math question?

  • cyankatcyankat Registered User Posts: 27 Junior Member
    x times x times x is not less than just x
  • RhythmMeleonRhythmMeleon Registered User Posts: 481 Member
    that proves that C is right.
  • SolateSolate Registered User Posts: 37 Junior Member
    I think the "right" answer is wrong

    A. Example x= 2 ~~~ 2 < 4 < 8
    B. Example x= -.5 ~~~ -.5< -.125 < .25
    C
    D. Example x= -2 ~~~ -8 < -2 < 4
    E. Example x=.9 ~~~~ .729 < .81 < .9
  • DrSteveDrSteve Registered User Posts: 1,289 Senior Member
    Try 1 of each "type" of number. There are 4 "types" that I have in mind:

    Numbers greater than 1, between 0 and 1, between -1 and 0, and less than -1.

    So for example, try 2, 1/2, -1/2, and -2. Each of these numbers will eliminate one answer choice, and you will be left with the answer.

    Remark: I suppose I should mention that there are 3 more "degenerate types": 1, -1, and 0. But these are not needed in this problem.
  • RhythmMeleonRhythmMeleon Registered User Posts: 481 Member
    C)
    Using 2: 4<8<2
    Using 1/2: 1/4<1/8<1/2
    Using -1/2: 1/4<-/18<-/12
    Using -2: 4<-8<-2

    D)
    Using 2: 8<2<4
    Using 1/2: 1/8<1/2<1/4
    Using -1/2: -1/8<-1/2<1/4
    Using -2: -8<-2<4 <
    THIS WORKS! ?? So how is D right?
  • RhythmMeleonRhythmMeleon Registered User Posts: 481 Member
    so sorry guys. I marked myself wrong, C is the correct answer
This discussion has been closed.