Question 10409: I have just started using the TI84 plus and we are supposed to use a graphing utility to aprox the real solution rounded 2 dec places. all solutions lie between -10 and 10.
x^3-4x+2=0
It says use (Zero or Root) on the graph of y1=
I dont understand this at all. Can anyone help me?
Tina
Answer by rapaljer(4671)   (Show Source):
You can put this solution on YOUR website! First use the TI 84 to sketch the graph of  in a standard window of the calculator. From looking at the graph you will be able to see approximately where the roots are (that is, where the graph crosses the x-axis). You will have to find these roots one at a time by the method described below.
Next use [2nd] [F2 (Calc)] and a menu drops down in which #2 should be "Zeros". Either bring the cursor down or type the number 2, and press [ENTER].
The calculator now is asking you for a "left bound". This means to decide which zero you want to find first, and choose a value of x that is clearly to the left of that point. Type an x value, and press ENTER.
The calculator will now ask you for a "right bound". What this means is that you need to find a value of x that is clearly to the right of this zero, but before you get to the next zero (if there is another zero). Type in this value of x and press ENTER.
Next the calculator will ask if you want to take a "guess?", to which you can just press ENTER again, and the calculator will find the zero or root and write it for you in the lower left corner of the calculator.
If you have other questions, feel free to send them to my Email address, as well as post them to algebra.com.
R^2 at SCC
P.S. Because it will be another week before I get my TI 84, I can't check this with a TI 84, but I think the answers should be -2.21, .54, and 1.68.
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