CALC Menu - zero Example y = f(x) is given by CALC|zero can be used to find an x-intercept of a graph. Enter the given function into Y1 and use a ZOOM|ZStandard window. Go to CALC|zero.

Slide 2 CALC Menu - zero Example y = f(x) is given by The following calculator screen appears. Note that: (1) The function is shown at the top left of the screen. (2) There are three x-intercepts for this function. It is necessary to specify which intercept is to be found.

Slide 3 CALC Menu - zero Example y = f(x) is given by Identify the Left Bound, or an x-value to the left of the intercept. This can be done in two different ways. Use only one of the two methods on the next slide. Find the x-intercept that appears to be close to x = -1.

Slide 4 (1) Use the left arrow key to move the trace cursor to the left of the intercept and press ENTER. CALC Menu - zero Example y = f(x) is given by (2) A second method is to type in an x-value that is clearly to the left of the intercept, say x = -2. Enter -2 and then press ENTER. This is usually much faster.

Slide 5 Identify the Right Bound, or an x-value to the right of the intercept. Again, this can be done in two different ways. CALC Menu - zero Example y = f(x) is given by (1) Use the right arrow to move the cursor and press ENTER, or... (2) Press 0, then ENTER.

Method (1) Slide 6 CALC Menu - zero Method (2) Note that with either method, there are two arrows above the intercept pointing towards each other. If the x-value of the intercept is not between the arrows, start again with CALC|zero and redo the bounds.  

Slide 7 CALC Menu - zero The calculator now asks for a “Guess?”. Just press ENTER and the x-intercept is found to be (-1, 0). Example y = f(x) is given by Recall that the x-value of an x-intercept is also a zero of the function, thus the name of the menu command, and f(-1) = 0.

Slide 8 CALC Menu - zero Example y = f(x) is given by For practice, find the other two zeros using CALC|zero. Answers: x = -4, 1

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