Move the cursor onto a line of input, then hit the <enter> key on the keypad to evaluate the cell and produce the plot.

Plot[2*x^2-3*x-2,{x,-1,1}]

Plot[2*x^2-3*x-2,{x,-3,4}]

Excercise P.5.1

Plot[x^2-x-20,{x,-1.5,2}]

Excercise P.5.6

Plot[x*(3*x+11),{x,-5,2}]