The command below is a very common plotting format that will soon become familiar to you. (Note: this plot command assumes the above definition of y; if you have not executed a command defining y, scroll back and do it now.)
Plot[y, {x,-7,7}, PlotRange -> All]
There are some items to note in this plot command that are peculiar to Mathematica:
· Notice the square brackets, [ and ], around the arguments of the Plot
command. Also note {x,-7,7} specifies the domain of x. It is
important to remember when to use the different types of brackets.
Mathematica is very `narrow minded' about this.
· "PlotRange -> All" is a plotting option, telling Mathematica that---"yes,
we do want to see the entire graph". (Other plotting options will be
introduced as we need them.) The arrow (->) is created with the
"hyphen" followed by the "greater than" keys on the keyboard.
· Notice the upper case letters in Plot and PlotRange. This is typical of
all Mathematica functions and options; so get used to this! In contrast,
if YOU define a new function, like y above, you are free in the use of
upper and lower case letters.
Execute the plot command below to see what the graph of y looks like. (Select the command by clicking after it, and hit Enter).
Plot[y, {x,-7,7}, PlotRange -> All]
You can see that the graph depicts the essential character of function y.