**TI 89 Integral Contents**:

## TI 89 Integral Function for Definite Integrals

General steps for finding the value of a definite integral on the TI-89:

- Press the F3 button,
- Press the “2” button (or scroll down to
*2: ∫ ( integrate*then press the “ENTER” button.) - Type in your function in the form

∫ (f(x), x, a, b).

See below for a specific example of finding a TI 89 integral.

## Example #1: Definite Integral on the TI 89

**Example question:**Evaluate:

To put this in English, the question is asking you to find the definite integral of f(x) = x^{2} on the closed interval [1, 3] (1, 3 are called the bounds of integration).

Step 1: **Press the F3 button**:

Step 2: **Press “2”:**

Step 3: **Type in your function.** For this example, that’s x^{2}, so type in

**x ^ 2**

Your screen should look like this:

Step 4: **Type a comma, then type the letter x **.

Step 5: **Type a comma again, then type your bounds of integration.** The bounds of integration for this example are 1, 3 so type in

**1,3 **

(don’t forget to type in another comma to separate the bounds!).

Step 6: **Type a closing parenthesis. **Your formula should look like this:

Step 7: **Press ENTER.** The solution is 8.66667.

## TI 89 Integral: General Instructions for Antiderivatives

Indefinite integrals don’t have any bounds of integration. Follow the above steps to find indefinite integrals, omitting Step 5 (i.e. don’t type *a,b*).

**Example question:** What is the antiderivative of f(x) = 3x^{5}?

Step 1: **Press the F3 button.**.

Step 2: **Press “2”.**

Step 3: **Type in your function.** For this example, that’s 3x^{5}, so type in

**3 x ^ 5**

Step 4: **Type a comma, then type the letter x **.

Step 5: Type a closing parenthesis.

Step 7: **Press ENTER.** The solution the calculator gives is x^{6}/2.

When writing out your answer, don’t forget to add a “+ C” (Why add a + C?). The antiderivative is:

(x^{6}/2) + C.

## References

Images: TI-89 Simulator.