View Full Version : sat math question of the day

elizabeth

10-19-2013, 06:00 PM

If -4<a<1, then which one of the following is negative?

(I) (a+4)(a-1)

(II) (-4-a)(a-1)

(III) (-4-a)(1-a)

(A) I only

(B) II only

(C) III only

(D) I and II only

(E) I and III only

Thanks

kadence

10-19-2013, 06:01 PM

All of the choices can be interpreted as quadratic inequalities with roots a=-4 \ or \ a=1 . The leading coefficient(s) for (I) and (III) are positive while for (II) is negative.

Therefore, for (I) and (III) we have the following sign diagram

---(+)--------{-4}---------(-)-------------{1}-------(+)---------

While for (II) we have the following sign diagram

---(-)--------{-4}---------(+)-------------{1}-------(-)---------

Therefore the correct answer is (E).

Hope these help!!

elizabeth

10-19-2013, 06:02 PM

Thanks a lot for your reply!!;)

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