Chapter 16

GRAPHING FUNCTIONS

Graphing linear equations—and therefore graphing linear functions—is a

straightforward task. There are numerous techniques by which the graphs

can be constructed (described in Chapter 5), but the behavior of a linear

graph is predictable. Other functions, however, present a challenge. Cubic,

absolute value, and square root functions, to name a few, have distinctly dif-

ferent graphs.

Rather than design algorithms by which each classiﬁcation of function

should be graphed, it is more useful to use one of two techniques to plot

function graphs: completing a table of values (that is, the brute force tech-

nique) to plot an extremely accurate graph or applying function transfor-

mations to create a relatively accurate sketch of the graph quickly.

Graphing functions is tricky. It wouldn’t be if all functions were lines,

because let’s face it, linear graphs are the easiest to create. All you need is

one point and the slope of the line and you’re in business! However, most functions

aren’t linear, so you need a few more graphing strategies.

There are basically two ways to draw a function graph. One is to plug in a lot

of x-values into a function f(x) to see what numbers you get as a result. Plug in

enough x’s and you can connect the dots to make a graph. The downside? A lot

of calculations and a big time investment.

There is a faster way to graph that involves memorizing a few basic function

graphs and then using transformations to stretch, squish, move, and ip them

to make new graphs. For example, after you memorize the simple graph of y = x

3

,

you can graph things like f(x) = x

3

+ 6, g(x) = (x – 7)

3

, and h(x) = –2x

3

in the blink

of an eye.

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