If xy > 0, which of the following must be negative?
Choose the correct choice from the following options
A) x+y B) x-y C) -xy D) -x * -y E) x/y
x,y must both positive or both negative. so that mn &gt; 0 is true   positive * negative = negative   Answer : -xy
<result>C</result>
If xy > 0, which of the following must be negative?