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Ch. 5 - Integration
5์žฅ, ๋ฌธ์ œ 5.2.51a

Properties of integrals Use only the fact that โˆซโ‚€โด 3๐“ (4 โ€•๐“) d๐“ = 32, and the definitions and properties of integrals, to evaluate the following integrals, if possible.
(a) โˆซโ‚„โฐ 3๐“(4 โ€• ๐“) d(๐“)

๊ฒ€์ฆ๋œ ๋‹จ๊ณ„๋ณ„ ์•ˆ๋‚ด
1
Step 1: Recognize the integral given in part (a) is the same as the integral provided in the problem, except the limits of integration are reversed. The integral provided is โˆซโ‚€โด 3๐“(4 โ€• ๐“) d๐“ = 32.
Step 2: Recall the property of definite integrals: reversing the limits of integration changes the sign of the integral. Mathematically, โˆซโ‚แต‡ f(๐“) d๐“ = -โˆซแต‡โ‚ f(๐“) d๐“.
Step 3: Apply this property to the integral in part (a). Since the limits are reversed (from 4 to 0 instead of 0 to 4), the integral becomes -โˆซโ‚€โด 3๐“(4 โ€• ๐“) d๐“.
Step 4: Substitute the value of the original integral, which is given as 32. Therefore, the integral in part (a) becomes -32.
Step 5: Conclude that the integral โˆซโ‚„โฐ 3๐“(4 โ€• ๐“) d๐“ evaluates to -32 based on the properties of integrals and the given information.

๋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:
1m
๋„์›€์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.

Definite Integral

A definite integral represents the signed area under a curve defined by a function over a specific interval. It is denoted as โˆซโ‚แต‡ f(x) dx, where 'a' and 'b' are the limits of integration. The value of a definite integral can be interpreted as the accumulation of quantities, such as area, over the interval from 'a' to 'b'.
์ถ”์ฒœ ์˜์ƒ:
๊ฐ€์ด๋“œ ์ฝ”์Šค
05:43
Definition of the Definite Integral

Properties of Integrals

The properties of integrals include linearity, which allows for the integration of sums and scalar multiples, and the reversal of limits, which states that โˆซโ‚แต‡ f(x) dx = -โˆซแต‡โ‚ f(x) dx. These properties enable the evaluation of integrals by transforming them into simpler forms or by changing the limits of integration.
์ถ”์ฒœ ์˜์ƒ:

Substitution in Integrals

Substitution is a technique used in integration to simplify the integrand by changing variables. This method involves selecting a new variable that simplifies the integral, allowing for easier computation. For example, if u = g(x), then dx can be expressed in terms of du, transforming the integral into a more manageable form.
์ถ”์ฒœ ์˜์ƒ:
04:27
Substitution With an Extra Variable
๊ด€๋ จ ์‹ค์ฒœ
๊ต๊ณผ์„œ ์งˆ๋ฌธ

Suppose ฦ’ is an odd function, โˆซโ‚€โด ฦ’(๐“) d๐“ = 3 , and โˆซโ‚€โธ ฦ’(๐“) d๐“ = 9 .


(a) Evaluate โˆซโ‚‹โ‚ˆโด ฦ’(๐“) d๐“ .

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๊ต๊ณผ์„œ ์งˆ๋ฌธ

Free fall On October 14, 2012, Felix Baumgartner stepped off a balloon capsule at an altitude of almost 39 km above Earthโ€™s surface and began his free fall. His velocity in m/s during the fall is given in the figure. It is claimed that Felix reached the speed of sound 34 seconds into his fall and that he continued to fall at supersonic speed for 30 seconds. (Source: http://www.redbullstratos.com)

(a) Divide the interval [34, 64] into n = 5 subintervals with the gridpoints xโ‚€ = 34 , xโ‚ = 40 , xโ‚‚ = 46 , xโ‚ƒ = 52 , xโ‚„ = 58 , and xโ‚… = 64. Use left and right Riemann sums to estimate how far Felix fell while traveling at supersonic speed.

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๊ต๊ณผ์„œ ์งˆ๋ฌธ

Area functions The graph of ฦ’ is shown in the figure. Let A(x) = โˆซโ‚€หฃ ฦ’(t) dt and F(x) = โˆซโ‚‚หฃ ฦ’(t) dt be two area functions for ฦ’. Evaluate the following area functions.

(a) A(2)

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๊ต๊ณผ์„œ ์งˆ๋ฌธ

Area functions for the same linear function Let ฦ’(t) = 2t โ€• 2 and consider the two area functions A (๐“) = โˆซโ‚หฃ ฦ’(t) dt and F(๐“) = โˆซโ‚„หฃ ฦ’(t) dt .

(a) Evaluate A (2) and A (3). Then use geometry to find an expression for A (๐“) , for ๐“ โ‰ฅ 1 .

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๊ต๊ณผ์„œ ์งˆ๋ฌธ

Substitutions Suppose ฦ’ is an even function with โˆซโ‚€โธ ฦ’(๐“) d๐“ = 9 . Evaluate each integral.                                                                                                       

(a) โˆซยนโ‚‹โ‚ ๐“ฦ’(๐“ยฒ) d๐“

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๊ต๊ณผ์„œ ์งˆ๋ฌธ

Explain why or why not Determine whether the following statements are true and give an explanation or counterexample.

(a) If ฦ’ is a constant function on the interval [a,b], then the right and left Riemann sums give the exact value of โˆซโ‚แต‡ ฦ’(๐“) d๐“, for any positive integer n.

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