Exercise 23 Page 153

Two lines are parallel if their slopes are identical. Knowing this, let's start by labeling the lines.

We have been given two points on each line, so we have enough information to calculate their slopes using the Slope Formula. m=y_2- y_1/x_2- x_1 Note that when choosing points to substitute for ( x_1, y_1) and ( x_2, y_2), it does not matter which points on the line we choose, since the result will be the same. Let's start with a line, which passes through ( -5, 2) and ( -4, -1).

The slope of line a line is -3. We will use the same method to identify the slopes of lines b and c

Now that we have identified the slope of each line, we can see that a and b line have the same slope, so they are parallel.