Algebra Know-It-ALL

322 Review Questions and Answers

That means Δy/Δx= 2/5, which is the slope of the line. The y-intercept is the y-value at Q,

becauseQ happens to lie on the y axis. That value is −1.

Question 15-2

In Fig. 20-5, how can we determine the slope of line QR? The y-intercept?

Answer 15-2

We know the ordered pairs for the two points as Q= (0,−1) and R= (2,4). Therefore,

Δy= 4 − (−1)

= 4 + 1

= 5

and

Δx= 2 − 0

= 2

That means Δy/Δx= 5/2, which is the slope of the line. As with line PQ, the y-intercept is −1,

which is the y-value at point Q.

–6 246

2

4

6

–2

–4

–6

–4 –2

x

y

P

Q

R

Figure 20-5 Illustration for Questions and Answers

15-1 through 15-10.