1.1. The product of 3 integer numbers is -5. What values can their sum take? Be sure to list all options.
Answer: 5 or -3 or -7

Solution. Since 5 is not divisible by any number other than 1 and itself, the only three factors that give a product of 5 are 1, 1, and 5. Since the sign of the product is negative, either one or all three numbers are negative. We get the following options: $1+1-5=-3 ; 1-1+5=5$; $-1-1-5=-7$.