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elizabeth
10-19-2013, 07:00 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, 07:01 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, 07:02 PM
Thanks a lot for your reply!!;)