Answer:
4.5 units
Step-by-step explanation:
First, we need to draw the points (-3, -1) and (-1, -5) as follows
Therefore, the distance between the points is the length of the yellow line. This distance is the hypotenuse of a triangle with legs a and b.
The length of a is 2 and the length of b is 4
Then, using the Pythagorean theorem, we can calculate the length of c as follow

So, using the calculator, we get that the value of c is equal to

To find an approximate value for c, we will use the following:
We know that √16 = 4 and √25 = 5
Since 20 is between 16 and 25, the square root of 20 is a number between 4 and 5, so we can approximate it to 4.5.
Therefore,
c = 4.5