Why Does My TI-89 Calculate Definite Integrals Instead of Indefinite?

[jaejoon89]

When I use the integral feature, my TI-89 is giving a numerical answer even if I'm not selecting any bounds for integration (i.e., if I'm just taking the antiderivative). It's as if there's an implicit integral or something. How do I change this so I can just get a normal antiderivative?

For example, if the function is x (or whatever) and I do int[x,x] it gives 1/32 instead of 1/2 x^2

 

[yyat]

You set x to 1/4, you need to clear that variable (on my TI92 that's delvar x).

 

[quicknote]

.

I understand your frustration with the integral feature on your TI-89 calculator. It is important to note that the calculator is programmed to give a numerical answer when no bounds are selected for integration. This is because the calculator is assuming that you want to evaluate the definite integral from negative infinity to positive infinity, which results in a numerical answer.

To change this and get a normal antiderivative, you can use the "nDeriv" function instead of the "int" function. The "nDeriv" function allows you to find the derivative of a function without specifying any bounds. This will give you the desired antiderivative result.

Alternatively, you can also manually input the bounds for integration when using the "int" function. For example, if you want to find the antiderivative of x, you can input "int[x,x,0,x]" which will give you the result of 1/2 x^2.

I hope this helps you to get the desired results from your TI-89 calculator. Remember to always double check your inputs and make sure you are using the correct function for the desired outcome.