Root/Zero of a Function


The following concepts are synonymous: horizontal intercept, root of a function, zero of a function.
Given y = f(x), a zero of f is an x-value such that f(x) = 0.

Press MENU 3 to access the GRPH-TBL menu. Then enter the function into the equation editor. For example, enter the function Y1 = x3 - 3x2 - 6x + 8. Press F5 to select DRAW. If needed, display the graph in the standard viewing window by pressing F2 to access the ZOOM menu, highlight B:QUICK, press the right thumb pad arrow, select 7:Std, and press EXE. The graph of the function in the standard viewing window is shown at right.

Press F4 to access the G-SLV menu, then press either 1 or EXE to select 1:Root. The screen then displays the left-most root in the viewing window. Moving from left to right, to display the next root, press the right thumb pad arrow once. Continue in like manner to see more displayed roots.

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