Question about Texas Instruments TI-84 Plus Calculator

# WHen I use my intersect function to find intersection points, it asks "first curve" then "second curve" and it wont say anything after that. It just repeats "second curve" continuously. PLEASE HELP!

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The curve is refering to the function. So you have two different "lines". You choose intersect then one line, then it will ask for the other line, then a guess. your guess may or may not matter if there is only 1 intersection it will only calculate faster. If there is more than one intersection it will let you choose which one you want.

Basically you can graph 1,2,3,4,5 or how ever many lines it will take, but you may only want the intersect of 2 of them, thats why it asks.

hope this helps

Posted on Apr 27, 2010

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## Related Questions:

### Why does ti83 ask if you want to guess?

Here you are trying to find the intersection point between two curves. Since you could have drawn more than 2 curves, the calculator gives you the opportunity to choose the first curve using the arrow Up/ arrow down to select.

Once the curves are chosen, the calculator wants to know where (in the world is Carmen Sandiego) is the intersection point. And no it is not asking you to give the position, just what are the leftmost (1st guess) and rightmost (2nd guess) limits of the interval where the intersection point is. You use the left arrow to go a bit to the left of the intersection point (which you see on the graph) and press ENTER. Then you do the same for the 2nd guess.

Dec 03, 2013 | Texas Instruments TI-84 Plus Calculator

### Why does it ask if you want to guess when graphing

Here you are trying to find the intersection point between two curves. Since you could have drawn more than 2 curves, the calculator gives you the opportunity to choose the first curve using the arrow Up/ arrow down to select.

Once the curves are chosen, the calculator wants to know where (in the world is Carmen Sandiego) is the intersection point. And no it is not asking you to give the position, just what are the leftmost (1st guess) and rightmost (2nd guess) limits of the interval where the intersection point is. You use the left arrow to go a bit to the left of the intersection point (which you see on the graph) and press ENTER. Then you do the same for the 2nd guess.

Dec 03, 2013 | Texas Instruments TI-83 Plus Calculator

### When I try to find Intercept on my graph I : [2nd]Trace [Enter] (for first curve) [Enter] (for second curve) but nothing happens. It still asks me for second curve. I move the point to diffrent...

There seems to be a confusion between two terms: intersection of two curves and y-intercept, or x-intercept.
When you press [2nd][TRACE] you are accessing the CALCulations menu for the graphics. The [1:calculate ] sub-menu gives the value of y for a given value of x. The first curve taken is the one in Y1=. If you want to find the value of y on a second curve for the same value of x, you use the Up Arrow or Down Arrow. (Use Up Arrow or Down Arrow to cycle through the curves.)
The sub-menu [5:Intersect] allows you to find a point where two curves intersect (cut one another). The calculator starts on the first curve (Y1=) and asks you to select the second curve. At this point you use the Up or Down arrow to jump tho the next curve. Then you will be asked for a guess.
First, know what you want and do not confuse interCEPT with interSECT

Jul 05, 2011 | Texas Instruments TI-84 Plus Calculator

### Why wont my calulator let me enter a second guess when finding the intercept on my graph?

To find the intersection (read interSECTION) of two curves you are prompted once for an initial guess. If the calculator does not find the intersection point , or if there are more than one intersection points, you have to restart the procedure.
For your information, the interCEPT (or y-intercept) is the ordinate of the point where a curve cuts the y-axis. It is easy to mistake one word for the other. They are not synonymous.

Jul 05, 2011 | Texas Instruments TI-84 Plus Calculator

I believe I already showed you with a profusion of details how to graph functions on the calculator. It would very kind of you to refer to the post that answered your question, so as not to make us answer it all over again. Much appreciated.

Read the following to use the intersection function.
1. You draw two or more graphs.
2. After the graphs are displayed, press [2nd][TRACE] to access the (CALC)ulate menu.
3. Select [5:Interesct]
4. You will be prompted for a first curve: the equation of the curve will be displayed at the top left corner of the screen. If it is one the intersecting curves, press [ENTER]
5. You will be prompted for the second curve. (You can move from one curve to another by pressing the UpArrow or DownArrow).
6. After two curves are selected, you will be prompted for a guess for the X-value of an intersection point: you can use the keypad to enter a guess or use the left or right arrow to move the cursor towards a point of your choosing (if there are more than one point).
7. After a short while the calculator gives you a solution.
8. If it fails, you must make a better guess.

Here are some screen captures

May 12, 2010 | Texas Instruments TI-83 Plus Calculator

### How do I use the intersect function on the TI-84 plus calculator

1. You draw two or more graphs.
2. After the graphs are displayed, press [2nd][TRACE] to access the (CALC)ulate menu.
3. Select [5:Interesct]
4. You will be prompted for a first curve: the equation of the curve will be displayed at the top left corner of the screen. If it is one the intersecting curves, press [ENTER]
5. You will be prompted for the second curve. (You can move from one curve to another by pressing the UpArrow or DownArrow).
6. After two curves are selected, you will be prompted for a guess for the X-value of an intersection point: you can use the keypad to enter a guess or use the left or right arrow to move the cursor towards a point of your choosing (if there are more than one point).
7. After a short while the calculator gives you a solution.
8. If it fails, you must make a better guess.

Apr 19, 2010 | Texas Instruments TI-84 Plus Calculator

### When you have a problem like that ex: 5-x^2 = x -9, how do you know what to set the ymin, ymax at in order to get ur answers to solve

Half of the work involved in solving a problem is being able to formulate it so that it can be solved. I am afraid your formulation leaves too many details in the dark.
But I think I figured out what you want.
"You want to solve the equation graphically, ie find the zeros of a function"

FIRST METHOD
1. Create a single expression from the equation : gather all terms on one side so as to make "expression"=0
2. One such expression is X^2 +X -14=0
3. Draw the function y=X^2+X-14
4. Find the X-coordinates of the points where y=0
If that is the method you had in mind, it does not matter what specific values you set for Ymin and Ymax, because you are interested in Y values near Zero. You have to make sure the X-axis appears on the screen.
I assume you know how to use the [2nd][TRACE] (CALC) [2:Zero] function to find the zeros.

Here is the negative one Here is the positive one

SECOND METHOD
The second method entails
1. defining two functions, Y1=-X^2+5 and Y2=X-9,
2. Graphing the two functions.
3. Finding their intersections.
4. The X-Values of the two points of intersection of Y1 and Y2 are the solutions of the equation.
Here is the graph in standard window dimensions

As you see, one root does not show and you have either to Zoom out or move the Yrange downward (as seen on the right picture for which I set Ymin=-15, Ymax=5

I assume you know how to find the intersection of the two curves, and I will show you only one point.
To find the intersection you use the [2nd][TRACE] (CALC) [5:Intersect] command

Jan 29, 2010 | Texas Instruments TI-84 Plus Calculator

### I graph two rational equations (both the positive and negative versions) which ceate circles. I then try to find the intersection of the two circles (2 points of intersections) using the intersect function...

Hi,
You should check your understanding of what a function is. You are drawing two functions the ranges of which do not overlap, since one branch is positive and the other is negative. You know that the only two points where there could be overlapping are the points where y=0 for both functions. Why would you need the calculator to confirm to you what you already know.
To define the two branches you had to take the square root of some expression say y= SQRT(5-x^2). That is a circle centered on O(0,0) with radius SQRT(5). The two points where the positive branch intersects the negative one are for y=0, meaning x1= SQRT(5) or x2= -SQRT(5).
What do you think is the exact value of SQRT(5): 2.236067977....? No, because SQRT(5) is an irrational number that has an infinite number of digits and no matter how many additional digits you may align to determine it will not make that representation the EXACT value of SQRT(5).

That does not mean you will never be able to find an intersection of the two curves. Maybe, if you take y=SQRT(4-x^ 2) the calculator will be able to find the intersections but that will remain one case.In general the calculator will not find the intersection.

I hope that I convinced that it is futile to seek, with the help of the calculator, the intersection of two irrational functions ( for they are irrational not rational as you claim) that share only two points.

Hope it helps.

Dec 03, 2009 | Texas Instruments TI-84 Plus Calculator

### How to find area between 2 curves

Hi,
The TI84Plus has a Shade( function which allows you to represent the area you want to calculate.
The simplest syntax of the command is

Shade( lower_function, upper_function, Xleft, Xright, pattern, patern_resol) where Xleft is the left limit, Xright is the right limit, pattern is the shading pattern and pattern_resol is the resolution of the shading. Only the area where lower_function is less than upper_function is shaded. Unfortunately this command does give the value of the shaded area.

To find the area between two curves
1. Draw the curves
2. Find the left intersection point using [2nd][CALC][5:intersect]. Sorry I will not describe the procedure. The X value of the intersection point is stored in Ans memory.
3. Press [2nd][QUIT] to go to main calculator screen.
4. Store the Ans result in say A: [2nd][Ans][STO->][ALPHA] A
6. Find a second intersection point. Result is stored in Ans memory.
8. Press [2nd][Ans][STO->][ALPHA] B to store the X value of the second intersection point in B.
9. Use the CATALOG to paste the fnInt( command to calculate the integral : [2nd][CATALOG][[APLHA] F and scroll to select fnInt( and press [ENTER]
10. To complete the command you need the identifiers Y1 and Y2.. You access the identifiers Y1 and Y2 by pressing [VARS][Y-VARS][1:Function][1:Y1] and [VARS][Y-VARS][1:Function][2:Y2]
11. The command should appear as fnInt( Y2-Y1,A,B)
12. Press [ENTER] to obtain your value.
Hope it helps.
Thank you for using FixYa.
Do not forget to rate the solution.

Dec 03, 2009 | Texas Instruments TI-83 Plus Calculator

### My TI 84 Plus Caluclator

Hello,
The function Intersect from the CALCULATE menu finf the coordinates of a point at which two or more curves intersect.
To use it:
1. Draw the functions.

2. Press [2nd][CALC][5:Intersect]

The cursor is on one of the curves. Read the equation top of the screen. If it is one of the curves you want press [ENTER]. The cursor jumps to another curve (in this case the only other curve).

Read the equation on top of the screen to verify thst it is the correct one. Press [ENTER]. The calculator asks asks for a guess of the coordinates of the intersection point.

As the intersection point is to the left of the current cursor position, use the left arrow to move cursor closer to the point.

Press [ENTER], and wait for the solution. Here it is.

In your question you talk about y intercept. If you want to calculate the ordinate of the point where a curve intersects the Y-axis, it is more efficient to use the [2nd][CAL][1:Value] selection.

You enter X=0 and press [ENTER]. The cursor jumps on the first curve (Y1=) an gives you the y-intercept.

Notice the position of cursor on graph. The y-value at the bottom is its ordinate.
To get the y-intercept of the second curve, leave the cursor on y axis and press the DownArrow. Cursor jumps to tthe second curve.
Since the X=0 is still stored, the value of y is displayed directly.

Hope it helps.

Oct 27, 2009 | Texas Instruments TI-84 Plus Calculator

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