# Interactive video lesson plan for: Pre-calculus-Polynomials- Using a graphing calculator to find zeros

#### Activity overview:

How to find zeros using a Ti-83 84 calculator
Welcome to MooMooMath Today I will walk you through how to find zero of a polynomial function.
I will go to y equals on the calculator and put in the function.
I will use the exponent key to put in x^3
I will put in x and the up arrow button for the exponent.
Next I will put in cubed.
I will next put in minus x ^2 and then -5x and finally 2.
I'm using an older calculator and I will redo it with a newer calculator
Before I hit graph I want to check my window.
I use the window at -9.4 and 9.4 on the x axis
I have an older calculator and there are 94 pixels along the window and it gives me friendlier answers.
If you put -10 and positive 10 for your min and max that will be fine.
Use a scale of 1 and the same on the y axis.
Uae a -10 and a positive 10 asyour min and max
You next will hit graph, and you will see the polynomial function.
I need to see where it is crossing the x axis.
Since I created a friendly window I can hit trace and I can use my left and right arrows to move my cursur.
This one is landing on -2,0
Scroll to the right, and the y intersect is crossing at 0,2
and it is crossing the x axis at .2 and .3 so there is probably an irrational number.
The last one crosses between 2 and 2.6 so it is another irrational number.
Now the only integer I have is x =2
So to get the other two I will use my zero key.
I will scroll to the left side and I will use second calc and find my zero.
I will use 2nd then trace because the second function is to calculate.
I will go down to zero and it is asking me for a left boundary.
I want to be on the left side of the zero and it gives me an arrow showing me that.
It will now give me x = .382 if I round it.
Then I will scrollto this one. I will hit trace, get my cursur on the curve and I will find this one.
I'm already on the left side so this time is underneath, I will hit 2nd and calc again.
Go to the zero and hit enter, asking me for the boundaries.
I'm on the let side.
Hit enter and go to the right side and hit enter and it give me an arrow to check my location.
I hit enter a third time and it gives me my zero 2.618
Those are my two zeros.
Now they are irrational and I could find those with sythetic division and the quadratic equation.
However, with a calculator I can just find it following those steps.
That is how you find zeros using a graphing calculator.
This one is a ti83 which is an older version.
I will complete another video on a newer graphing calculator.
It is the same the only difference is how you enter your equation.

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Tagged under: polynomials,pre-calculus,calculator, calculator,function,finding zeros,polynomial functions,zeros,graphing

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