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Quiz 6
1. A company installs underground cables at a cost of $\$300$ for the first $30$ feet and $\$6$ per foot after. Express the cost $C$ in terms of the lengths of table $L$ (for $L>30$ ft). What is the cost of $40$ feet of cable?
Solution: We write
$$C(L)=300+6(L-30).$$
The cost of $40$ feet of cable is $C(40)=300+6(40-30)=300+60=\$360$.
2. Sketch a picture of "all points whose $y$-coordinate is $2$".
Solution:
3. What is the $x$-coordinate of all points on the $y$-axis?
Solution: All points on the $y$-axis have $x$-coordinate $0$.
4. Draw a picture of all points whose $x$-coordinate is less than or equal to $8$.
Solution:
5. Graph the function $f(x)=x^3$ by plotting four points: one for $x=-1$, one for $x=0$, one for $x=1$, and one for $x=2$.
Solution: We make a table of values for these given points:
| $x$ | $f(x)$ |
| $-1$ | $(-1)^3=-1$ |
| $0$ | $0^3=0$ |
| $1$ | $1^3=1$ |
| $2$ | $2^3=8$ |
