MathRevolution wrote:

If rs>0, which of the following cannot be true?

A. r>0 B. s>0 C. r+s>0 D. r+s<0 E. r<0<s

If r*s is positive, r and s are either both positive or both negative.

Answer E says one is negative and the other is positive. Not possible.

Answers A through D can be true. For A and B, one variable can be positive if the other one is positive too. For C, r and s are both positive. For D, r and s are both negative.

Answer E

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