I. Entering the Function in the Graph Window
C. Rational Functions
Generally, when you enter a rational function it is safer to enter the function using parentheses around both the numerator and the denominator. If the numerator has only one term, parentheses are not necessary (shown in the first two examples.)
Example: Enter the functions shown.
No parentheses are 

Put parentheses around
the denominator. 

Put parentheses around
the numerator and denominator. 

Put parentheses around
the numerator and denominator. 

Functions entered. 