# How to Find the Area Over an Interval Using Integrals.

4,397

74

11

In this instuctable, you will be able to learn how to find the area under the curve using integrals.

### Teacher Notes

Teachers! Did you use this instructable in your classroom?
Add a Teacher Note to share how you incorporated it into your lesson.

• Paper
• Pencil
• Calculator
• Equation
• Interval

## Step 2: Know the Standard Form for Integrals.

The standard form for integrals is in the picture provided.

## Step 3: Come Up With an Equation.

For example, lets use the equation 9x^2-4x+2. plug this into your f(x).

## Step 4: Now Figure Out Over What Interval You Want to Find the Area Of.

So lets say you want to find the area between 1 and 5. Plug the value 1 in as your "a" and the value 5 as your "b"

## Step 5: Find the Integral of Your Equation.

For every 'x' in the equation, you will add n+1 to the exponent. After doing so, you will divide the coefficient (the number in front of that variable) by the new exponent. If there is a number without a variable, remember that it has a variable of x^0.

Example: 9x^2 would now be (9/3)x^3

## Step 6: Find the Area Over the Interval

With the new equation, you can now find the area over the interval. Take your value "b" and plug it into every variable 'x' of the equation. Do the same exact thing for your value "a." After, subtract your answer from the value "b" by your answer from "a" to get the area.

Example: f(b) - f(a)

## 11 Discussions

I think it's useful because it makes it clear what corresponds to a linear integral, but you can not understand how you get it nor even what is the differential. Like that, it's like believing to show the world the art of painting only showing Picasso...you just showed the process for a polynomial function, but things change when the function is exponential, rational, logarithmic ......