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Ch. 5 - Integration
5์žฅ, ๋ฌธ์ œ 5.R.9a

Integration by Riemann sums Consider the integral โˆซโ‚โด (3๐“โ€• 2) d๐“.


(a) Evaluate the right Riemann sum for the integral with n = 3 .

๊ฒ€์ฆ๋œ ๋‹จ๊ณ„๋ณ„ ์•ˆ๋‚ด
1
Step 1: Understand the problem. The integral โˆซโ‚โด (3๐“ - 2) d๐“ represents the area under the curve of the function f(๐“) = 3๐“ - 2 from ๐“ = 1 to ๐“ = 4. To approximate this integral using the right Riemann sum, we divide the interval [1, 4] into n = 3 subintervals.
Step 2: Determine the width of each subinterval. The width of each subinterval, ฮ”๐“, is calculated as ฮ”๐“ = (b - a) / n, where a = 1, b = 4, and n = 3. Substitute these values into the formula to find ฮ”๐“.
Step 3: Identify the right endpoints of each subinterval. The right endpoints are the values of ๐“ at the end of each subinterval. For n = 3, the subintervals are [1, 2], [2, 3], and [3, 4]. The right endpoints are ๐“โ‚ = 2, ๐“โ‚‚ = 3, and ๐“โ‚ƒ = 4.
Step 4: Evaluate the function f(๐“) = 3๐“ - 2 at each right endpoint. Substitute ๐“โ‚, ๐“โ‚‚, and ๐“โ‚ƒ into the function to calculate f(๐“โ‚), f(๐“โ‚‚), and f(๐“โ‚ƒ).
Step 5: Compute the right Riemann sum. Multiply each function value f(๐“แตข) by the width ฮ”๐“, and then sum these products: Rโ‚ƒ = ฮ”๐“ ร— [f(๐“โ‚) + f(๐“โ‚‚) + f(๐“โ‚ƒ)]. This gives the approximation of the integral using the right Riemann sum.

๋น„์Šทํ•œ ๋ฌธ์ œ์— ๋Œ€ํ•œ ๊ฒ€์ฆ๋œ ์˜์ƒ ๋‹ต๋ณ€:

์ด ์˜์ƒ ํ•ด๋ฒ•์€ ์œ„ ๋ฌธ์ œ์— ๋„์›€์ด ๋œ๋‹ค๊ณ  ํŠœํ„ฐ๋“ค์ด ์ถ”์ฒœํ•œ ๊ฒƒ์ž…๋‹ˆ๋‹ค.
์˜์ƒ ๊ธธ์ด:
3m
๋„์›€์ด ๋˜์—ˆ๋‚˜์š”?

์ฃผ์š” ๊ฐœ๋…

์งˆ๋ฌธ์— ์˜ฌ๋ฐ”๋ฅด๊ฒŒ ๋‹ตํ•˜๊ธฐ ์œ„ํ•ด ๋ฐ˜๋“œ์‹œ ์ดํ•ดํ•ด์•ผ ํ•˜๋Š” ํ•ต์‹ฌ ๊ฐœ๋…๋“ค์€ ๋‹ค์Œ๊ณผ ๊ฐ™์Šต๋‹ˆ๋‹ค.

Riemann Sums

Riemann sums are a method for approximating the value of a definite integral by dividing the area under a curve into small rectangles. The sum of the areas of these rectangles provides an estimate of the integral's value. Depending on the chosen points (left, right, or midpoint) for the height of the rectangles, different types of Riemann sums can be calculated, which converge to the exact value of the integral as the number of rectangles increases.
์ถ”์ฒœ ์˜์ƒ:
06:11
Introduction to Riemann Sums

Definite Integral

A definite integral represents the signed area under a curve defined by a function over a specific interval [a, b]. It is denoted as โˆซโ‚แต‡ f(x) dx and provides a numerical value that corresponds to the accumulation of quantities, such as area, over that interval. The Fundamental Theorem of Calculus connects differentiation and integration, stating that the definite integral can be evaluated using antiderivatives.
์ถ”์ฒœ ์˜์ƒ:
05:43
Definition of the Definite Integral

Partitioning the Interval

Partitioning the interval involves dividing the range of integration into smaller subintervals, which is essential for calculating Riemann sums. For n subintervals, the width of each subinterval is ฮ”x = (b - a)/n. In this case, with n = 3 for the integral from 1 to 4, the interval is divided into three equal parts, allowing for the evaluation of the function at specific points to approximate the area under the curve.
์ถ”์ฒœ ์˜์ƒ:
08:44
Interval of Convergence
๊ด€๋ จ ์‹ค์ฒœ
๊ต๊ณผ์„œ ์งˆ๋ฌธ

Area functions and the Fundamental Theorem Consider the function

ฦ’(t) = { t      if  โ€•2 โ‰ค t < 0

tยฒ/2    if    0 โ‰ค t โ‰ค 2

and its graph shown below. Let F(๐“) = โˆซโ‚‹โ‚หฃ ฦ’(t) dt and G(๐“) = โˆซโ‚‹โ‚‚หฃ ฦ’(t) dt.                                                                                                               

                                                                                                                                                                               


(a) Evaluate F(โ€•2) and F(2).

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๊ต๊ณผ์„œ ์งˆ๋ฌธ

Evaluating integrals Evaluate the following integrals.


โˆซโ‚โด ((โˆšv + v) / v ) dv

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๊ต๊ณผ์„œ ์งˆ๋ฌธ

Consider the function

ฦ’(t) = { t      if  โ€•2 โ‰ค t < 0

tยฒ/2    if    0 โ‰ค t โ‰ค 2                                                                                                                                                                       

and its graph shown below. Let F(๐“) = โˆซโ‚‹โ‚หฃ ฦ’(t) dt and G(๐“) = โˆซโ‚‹โ‚‚หฃ ฦ’(t) dt.

(f) Find a constant C such that F(๐“) = G(๐“) + C .

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๊ต๊ณผ์„œ ์งˆ๋ฌธ

Evaluating integrals Evaluate the following integrals.


โˆซโ‚€โต |2๐“โ€•8|d๐“

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๊ต๊ณผ์„œ ์งˆ๋ฌธ

Evaluating integrals Evaluate the following integrals.


โˆซโ‚แต‰ d๐“ / [๐“(1 + ln ๐“)]

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๊ต๊ณผ์„œ ์งˆ๋ฌธ

Evaluating integrals Evaluate the following integrals.                                                                                                                                         

                                                                                                                                                                    

 โˆซ d๐“/[(tanโปยน ๐“) (1 + ๐“ยฒ)]

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