Zero of a Function

First, enter the function into the Y= editor and GRAPH the function. From the graph window, press to access the Math menu. Then press to access 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 to access the Math menu, then press to select 2: Zero.

The question "Lower 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. The "1" in the upper right-hand corner of the graph screen indicates finding an x-intercept on the graph of the first active function, y1.

Let's 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 "Upper Bound?" appears at the bottom of the screen. Use the thumb pad arrows to move the blinking cursor just to the right of the desired x-intercept, then press .

The coordinates of the x-intercept appear at the bottom of the screen: xc:4, yc:0 means that the x-coordinate of the x-intercept is 4 and the y-coordinate is 0.

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