Calculating a Value for a Function
For the function representated symbollically, f(x) = -3x + 17, find f(3). To find f(3), Press , and enter -3x + 17 for . Choose a window that includes the x-value at which the function will be evaluated, then graph the function. In our case since we need to evaluate the function at x = 3, press ZOOM, and the press 6 to graph in a standard window. Next press 2nd TRACE[Calc] to get the calculate menu. Press ENTER to accept the selection of 1:value. Type 3 next to the X= at the bottom of the screen and then press ENTER.
A Y=8 appears at the bottom of the screen. That means, for this function, when x = 3, y = 8.
Two other ways to say that are that (3, 8) is a point of this function and we can also say f(3) = 8.