Re: If ab is positive and cde is negative, which of the following must be
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31 Jan 2023, 12:21
OE
One approach to this problem is to pick numbers. However, this could lead to mistakes, or to multiple answer choices that seemingly lead to a correct answer. Since the choices largely concern the sign of various expressions, one could work with the signs of the variables. In either case, all positive/negative scenarios must be considered.
(A) ab + cde = Pos + Neg, which could be either positive or negative.
(B) ab × cde × cde = Pos × Neg × Neg, which must be positive.
(C) ac + de could be any sign, as a, c, d, and e are not constrained individually to one particular sign.
(D) ab/cde=Pos/neg= Neg but it could be > or < -1
(E) a/cde=Pos or Neg/Neg=Neg or Pos