Integral
The integral is one of the two base concepts of calculus, along with the derivative.
There are two types of integrals:
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[hide]Indefinite Integral
The indefinite integral, or antiderivative, is a partial inverse of the derivative. That is, if the derivative of a function is written as , then the indefinite integral of is , where is a real constant. This is because the integral of a constant is .
Notation
- The integral of a function is written as , where the means that the function is being integrated in relation to .
- Often, to save space, the integral of is written as , the integral of as , etc.
Rules of Indefinite Integrals
- for a constant and another constant .
- ,
Definite Integral
The definite integral is also the area under a curve between two points and . For example, the area under the curve between and is , as are below the x-axis is taken as negative area.
Definition and Notation
- The definite integral of a function between and is written as .
- , where is the antiderivative of . This is also notated $\int f(x)\,dx \eval^{b}_{a}$ (Error compiling LaTeX. Unknown error_msg), read as "The integral of evaluated at and ." Note that this means in definite integration, one need not add a constant, as the constants from the functions cancel out.
Rules of Definite Integrals
- for any .
Other uses
- The word integral is the adjectival form of the noun "integer." Thus, is integral while is not.