Zero of a Function

First, enter the function into the Y= editor and GRAPH the function. From the graph window, press CALC to access the calculate menu. Press to select 2: Zero. A zero or root of a function f is an input value x such that f(x)=0. The zero option is used to find an x-intercept.

For example, enter the function and graph the function in the standard viewing window. Then, from the graph window, press CALC to access the calculate menu, then press to select 2: Zero.

The question "Left Bound?" appears at the bottom of the screen. Since a function may have more than one x-intercept, specify an interval containing the desired x-intercept. LetÕs find the rightmost x-intercept. Use the thumb pad arrows to move the blinking cursor to the left of the rightmost x-intercept, but not including any other x-intercept, then press .

The question "Right Bound?" appears at the bottom of the screen. Use the thumb pad arrows to move the blinking cursor just to the right of the x-intercept, then press . You are now prompted for a Guess?. Enter an x-value anywhere between the left and right bounds. Here, weÕll enter 3.8 .

The coordinates of the x-intercept appear at the bottom of the screen: X=4, Y=0.

Note Alternatively, one may obtain a zero of a function algebraically rather than geometrically. To find a zero for a function f, one may simply solve the equation f(x)=0.