Algebra Know-It-ALL

318 Review Questions and Answers

Answer 14-1

The first quadrant of the Cartesian plane is usually the one at the upper right, and both

variables are positive. In the second quadrant, which is usually at the upper left, the inde-

pendent variable is negative and the dependent variable is positive. In the third quadrant,

which is usually at the lower left, both variables are negative. In the fourth quadrant, which

is usually at the lower right, the independent variable is positive and the dependent variable

is negative.

Question 14-2

Figure 20-3 shows three points, called P,Q, and R, plotted in the Cartesian plane. In which

quadrants do these points lie? What are the ordered pairs representing these points?

Answer 14-2

Point P is in the third quadrant, and is represented by the ordered pair (−5,−3). Point Q is not

in any quadrant because it is directly on one of the axes; it is represented by (0,−1). Point R is

in the first quadrant, and is represented by (2,4).

Question 14-3

Imagine horizontal lines (that is, lines parallel to the x axis) running through each of the

three points in Fig. 20-3. What are the equations of these lines? Do any of them represent

functions of x?

–6 246

2

4

6

–2

–4

–6

–4 –2

P

Q

R

x

y

Figure 20-3 Illustration for Questions and Answers

14-2 through 14-6.