When we multiply one integer by another, we add or subtract as many copies of one integer as indicated by the other.
- 20
Practice makes perfect
We can begin by considering the given product.
4( - 5)We want to find the product of 4 and - 5. To do so, we will use a number line. Notice that the first integer, 4, is positive. This means that to represent the product on the number line, we will add 4 copies of the second integer, - 5. Let's start by drawing an arrow from 0 to the - 5.
Notice that the arrow that represents adding - 5 one time ends at - 5. In our case, we want to add - 5 four times. Let's mark this on the number line!
From the diagram, we can see that the last arrow ends at - 20. This means that the product of 4 and - 5 is equal to - 20.
Checking Our Answer
Let's check our answer, just to be sure. Recall the rules for the multiplication of integers.
The product of two integers with the same sign is positive.
2* 3=6
Multiplying Integers with Different Signs
The product of two integers with different signs is negative.
2* (- 3)=- 6
Let's take a look at the given product!
4( - 5)
Notice that the integers in our expression have different signs. This means that their product will have a negative sign. Let's perform the multiplication.
4( - 5)= - 20
We found that the product of 4 and - 5 is to - 20. Our answer was correct!
