Is the Limit Definition of a Definite Integral Correct?

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In summary, the equation \int^{b}_{a} f(x) dx = lim_{c → a^{+}} lim_{d → b^{-}} \int^{d}_{c} f(x) dx is always true, regardless of whether f(x) is continuous on the interval [a,b] or (a,b). This is because in the first case, the limit is the value of the primitive F(x) at either a or b, and in the second case, the limit is used to determine if the result is a finite value for the improper integral.
  • #1
GreenPrint
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[itex]\int^{b}_{a}[/itex] f(x) dx = [itex]lim_{c → a^{+}}[/itex] [itex]lim_{d → b^{-}}[/itex] [itex]\int^{d}_{c}[/itex] f(x) dx

Is this true?
 
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  • #2
GreenPrint said:
[itex]\int^{b}_{a}[/itex] f(x) dx = [itex]lim_{c → a^{+}}[/itex] [itex]lim_{d → b^{-}}[/itex] [itex]\int^{d}_{c}[/itex] f(x) dx

Is this true?

What are the arguments of the limit in this case?
 
  • #3
HACR said:
What are the arguments of the limit in this case?

a and b on the left hand side and I replaced these with c and d evaluated with limits with a and b, a from the right and b from the left.
 
  • #4
Yes it always true, either if f(x) is continuos on [a,b] or on (a,b). In the first case you have a proper integral, in fact the primitive F(x) is also continuos and the limit is the value of F at a (or b). In the second case you have an improper integral and in that case is necessary to use the limit to check whether or not the result is a finite value.
 
  • #5
hmmm...
ya i guess so thanks
 

FAQ: Is the Limit Definition of a Definite Integral Correct?

What is integration?

Integration is a mathematical process that involves finding the area under a curve. It is often used to find the total value of a quantity that is changing over a period of time, or to calculate the volume of an irregular shape.

Why is integration important?

Integration is important because it allows us to solve a variety of real-world problems, such as finding the distance traveled by a moving object, the volume of a complex shape, or the total amount of change in a system. It is also a fundamental tool in calculus and other branches of mathematics.

What are the different methods of integration?

There are several methods of integration, including the fundamental theorem of calculus, u-substitution, integration by parts, and integration by partial fractions. These methods are used to solve different types of integrals, depending on the complexity of the function.

How is integration related to differentiation?

Integration and differentiation are inverse operations of each other. This means that integration "undoes" differentiation, and vice versa. The derivative of a function is used to find its rate of change, while the integral of a function is used to find the accumulated change over a given interval.

What are some real-world applications of integration?

Integration is used in various fields of science, engineering, and economics. Some examples of real-world applications include calculating the displacement of an object in physics, determining the amount of medication in a patient's bloodstream in medicine, and finding the optimal production levels in business and economics.

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