Definite Integrals
Math vocabulary
derivative, integral, limit, general symbols, etc.
Properties of definite integral
if a<c<b then the definite integral over the interval (a;b) is equal to the definite integral over the interval (a;c) plus the definite integral over the interval (c;b)
the definite integral of the function f(x) plus g(x) equals to the sum of the two integrals of the singular functions in the same order and interval
if theres a constant in a integral it's possible to take it out the integral
if a function is less or equal to another one then the integrals are respectively less or equal to each other like the functions
Coventions
when the limits are the same [a;a] the integral equals to 0
Changing the upper and the lower limit the integral is the same by putting a minus ahead
Area under a curve
By approximation
divided area in inner or outer rectangles
By integration
definite integral of the function y=f(x) over the interval [a;b]
The solution of the definite integral is the antiderivative of f(x) over the interval [a;b]. Then substitute the upper limit (b) into the integral and subtract the value given by substituting the lower limit (a) into the integral
The function is not given
you need to find the equation of the function
The function is negative in the interval
you need to put an absolute value at the start or you need to change the sign at the end
The limits aren't given
you need to find the intersections with the x axis
Somtitimes positive sometimes negative
Area between two curves
If you have two functions f(x) greater or equal to g(x) over the interval [a;b] the area between them equals to the definite integral of f(x) minus g(x) over the interval [a;b]
Average value of a funcion
equals to the definite integral of f(x) over the interval [a;b] diivided by the upper limit minus the lower limit