334 Review Questions and Answers
left side of the equals sign. In Answer 16-4, that was done starting with the original equation. If
we start with the SI form with y as the dependent variable, we can do this:
y= (1/3)x+ 3
y− 3 = (1/3)x
3 y− 9 =x
x= 3 y− 9
This SI equation tells us that the x-intercept is equal to −9.
Question 17-6
How can we morph Fig. 20-6, the graph of the system from Question and Answer 17-1 and
Fig. 20-6, to get a graph that will show the same system with y as the independent variable
andx as the dependent variable?
Answer 17-6
We can use the rotate-and-mirror method. We start with Fig. 20-6 and rotate the entire
assembly as a single mass—axes, lines, and points—counterclockwise by a quarter-turn (90°).
Then we mirror the whole thing left-to-right. Finally, we reverse the ordered pairs to obtain
the new points. The result is shown in Fig. 20-7.
Question 17-7
What are the SI forms of the equations for the lines in Fig. 20-7?
Solution =
(2,–3)
(3,0) (8,0)
Each axis
increment
is 1 unit
x
y
Figure 20-7 Illustration for Questions and Answers
17-6 through 17-10.