Question about Texas Instruments TI-89 Calculator

# I am having trouble figuring out why my ti 89 has trouble figuring out integrals. for example i know that the integral of x^2 is x^3/3+c but my ti 89 gives me the answer in a decimal of fraction form. i do not understand why. this also happens when i am trying to factor or find zeros. but mainly, i need help why the integrals do not work. thank you

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• kakima May 11, 2010

Which form are you getting it, in decimal or fraction? Which way do you want it? Can you post exactly what you're entering and what the calculator is producing?

Press MODE, then F2. What is the Exact/Approx setting?

FYI my TI-89 produces x^3/3 when I integrate x^2.

• tang_lx1988 Mar 01, 2012

I typed in "F3 2 x ^ 2 , x )"then it gives me 2706867/15625

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### k24674

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The calculator does not give a result of an integration with a constant. The form of the result will depend ob the EXACT/APPROXIMATE mode you have selected.
In the following screen capture, your integral has been evaluated with mode set to EXACT,AUTO, and APPROXIMATE. Pay attention to the syntax. To set the computational mode to EXACT, press the MODE button use the Function keys F1,F2 or F3 to move from page to page, point to EXACT/APPROX and use the right arrow key to unfold the submenu, then the Up or Down arrow to select AUTO, EXACT or APPROXIMATE and press ENTER to SAVE Configuration.
If the integral cannot be found in EXACT mode, the calculator will echo the command without calculating the integral.

Posted on Apr 29, 2010

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× ## Related Questions:

### Integration

The integral cannot be calculated in terms of the elementary functions. It is given by dilogarithm Li_2. Note here that log stands for the natural logarithm (ln) ### My TI-89 does not calculate integrals, etc. for example Int(x) will result in Int(x)

Don't spell it out. Use the integral sign, available by pressing 2nd then 7.

For this example, press 2nd 7 2nd Y X ) , ) ENTER

2nd 7 gets you the integral, 2nd Y gets you the sine.

### Why wont my ti-89 integrate

It ts easy to find solution for this problem. Type int(sin(377x-1.231),x,0.299,3.94)
See captured image below ### Error: dependent limit

Dependent limit error may occur if a limit of integration is dependent on the integration variable.

For example, integral:

int(x^2,x,1,x) is not allowed

### I am not able to integration on my ti 89 titanium calculator...i mean its only solving simple ones and for the big ones like ((t+2)^(1/2))/e^t.....it completely messed up my calculus bc exam

Well it is just a calculator, it cannot do all the possible integrals you might think of. You may try to help it a bit by using the usual techniques that you were taught to transform the integral into another it might be able to find: change of variables, integration by parts. You cannot let the success on your AB or BC exam depend solely on the calculator.

### I put in my calculator integrate of (2^X) and the answer is root squere of 2/12 when theanswer should be X^3/3 how can I solve this, by the way my calculator is is a TI-89 Titanium

What do you really want to integrate? 2 to power x (2^x) or x squared (x^2). Look at the screen capture below. The command line shows you the syntax for an indefinite integral. ### When i do my integration problems i am getting my answers in decimal form. for example {S((lnx),x,1) = 0.}

What are you trying to do? The syntax you use depend on what you want to achieve.
Indefinite integral : Integral( ln(x),x) gives the correct answer xln(x)-x
Definite integral : Integral(ln(x),x,1,2) gives the integral of ln(x) between x=1 and x=2
Definite integral between 1 and y : Integral (ln(x), x,1,y) gives the correct expression yln(y)-y +1

By inserting the =0 you are in fact assigning the result of the integration to value 0, and the calculator calculates the integral and assigns 0 to it. This is what my TIVoyage 200 PLT gives me:
{Integral((lnx),x,1) = 0.} returns {x.ln(x)-x+1=0}
which is an equation.

### I am trying to get the answer to an indefinite integral. I keep getting "argument error" For example, I type in after the integral sign: (sin(x),x) and get the error message. Help!

You already have something stored with the name x. Either get rid of it or use a different name for the variable of integration.

You can see what variables you have stored by pressing 2ND [VAR-LINK] (the minus key).

### How to calculate a finite integral

Press 2ND MATH to bring up the Math menu. Select "Calculus" and then "integrate." Enter the expression, the variable of integration, the lower limit, and the upper limit, separated by commas. Close the final paren and press ENTER or diamond ENTER.

For example, to calculate the integral from 0 to pi of sin(x) dx, you want

INT(sin(x),x,0,pi)

where INT is the integral sign and pi is the lower-case Greek pi.

### Integration, too few arguments

I reset my calculator and this solved the problem. To reset your calculator press [2nd], then  (Mem), press F1 (reset), Select 3 for all memory, and select Yes.

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