Riemann Sum Definite Integral Question

In summary, the question asks to evaluate the integral (x-2)dx from -2 to 2 using the definition of a definite integral with an unspecified number of intervals. To solve this problem, one can pick n equally spaced rectangles, with each rectangle having a width of 4/n. By choosing the center as the coordinate for each rectangle, the height can be calculated by substituting the chosen x-value in (x-2). The sum of the areas of the rectangles can then be calculated and n can be let to approach infinity to find the value of the integral.
  • #1
ISITIEIW
17
0
So the question is Evaluate (x-2)dx as the integral goes from -2 to 2 using the definition of a definite integral, choosing your sample points to be the right endpoints of the subintervals…

Ok, so i understand how to do this problem if it gave me an actual number of interval like n=6 but it doesn't and I'm not sure how to go about actually solving it without an actual number for n.

Thanks :)
 
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  • #2
ISITIEIW said:
So the question is Evaluate (x-2)dx as the integral goes from -2 to 2 using the definition of a definite integral, choosing your sample points to be the right endpoints of the subintervals…

Ok, so i understand how to do this problem if it gave me an actual number of interval like n=6 but it doesn't and I'm not sure how to go about actually solving it without an actual number for n.

Thanks

Welcome to MHB, ISITIEIW! :)

I suggest you pick n equally spaced narrow rectangles numbered i = 1, ..., n.
To visualize it, you can start with n=6.
Then each rectangle will have width w=4/n.
For each rectangle we can pick an arbitrary coordinate $x_i$ between its left side and its right side. Say we pick the center, what would $x_i$ be then?
Substitute that $x_i$ in (x-2) and you get the height of each rectangle.

Can you calculate the sum of the areas of the rectangles?
And then let n go to infinity?
 

Related to Riemann Sum Definite Integral Question

What is a Riemann Sum?

A Riemann Sum is a method used to approximate the area under a curve by dividing the interval into smaller subintervals and summing the areas of the rectangles formed by those subintervals.

What is a Definite Integral?

A Definite Integral is a mathematical concept that calculates the precise area under a curve between two points on the x-axis. It is represented by the symbol ∫ and has a lower and upper limit.

How do I find the Riemann Sum for a Definite Integral?

To find the Riemann Sum for a Definite Integral, you first need to divide the interval into smaller subintervals. Then, you calculate the width of each subinterval and determine the height of the rectangles by plugging in the x-values into the function. Finally, you sum up the areas of all the rectangles to get the Riemann Sum.

What is the purpose of using Riemann Sums in finding Definite Integrals?

Riemann Sums are used to approximate the area under a curve when it is not possible to find the exact value using traditional integration methods. It helps to break down the area into smaller, manageable parts and find the sum of the areas of those parts.

Can a Riemann Sum be used to find the exact value of a Definite Integral?

No, a Riemann Sum can only approximate the value of a Definite Integral. To find the exact value, you would need to use other methods such as the Fundamental Theorem of Calculus or integration techniques like substitution or integration by parts.

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