Question

Reese needs to understand the integer laws to complete his homework. As he recites his rules, he is overheard saying "a positive plus a positive is positive, a negative plus a negative is negative, and a positive plus a negative is a negative". Is he right? Explain why or why not?

Answer 1

No

Explanation:

Let's check the first statement with an example. 2 and 3 are positive numbers and their sum (5) is also positive so his first statement is true.

To check the second statement let's look at the negative numbers -1 and -8 for example. Their sum (-9) is also negative so his second statement is true.

To check the third statement let's look at the numbers 9 and -5. One is positive and one is negative, but their sum (4) is positive, so his third statement is false. However if we look at the numbers 4 and -7, their sum is negative so the third statement is partially false.