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Ch. 5 - Integration
5์žฅ, ๋ฌธ์ œ 5.3.51c

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.


(c) โˆซโ‚„โฐ 6๐“(4 โ€• ๐“) d(๐“)

๊ฒ€์ฆ๋œ ๋‹จ๊ณ„๋ณ„ ์•ˆ๋‚ด
1
Step 1: Recognize that the integral given in the problem, โˆซโ‚„โฐ 6๐“(4 โ€• ๐“) d๐“, is related to the integral โˆซโ‚€โด 3๐“(4 โ€• ๐“) d๐“ = 32. Notice the limits of integration are reversed, and the integrand has been scaled by a factor of 2.
Step 2: Use the property of integrals that states reversing the limits of integration changes the sign of the integral. Specifically, โˆซโ‚แต‡ f(๐“) d๐“ = -โˆซแต‡โ‚ f(๐“) d๐“. Apply this property to rewrite โˆซโ‚„โฐ 6๐“(4 โ€• ๐“) d๐“ as -โˆซโ‚€โด 6๐“(4 โ€• ๐“) d๐“.
Step 3: Factor out the constant 6 from the integral using the property of integrals that allows constants to be factored out. This gives -6 โˆซโ‚€โด ๐“(4 โ€• ๐“) d๐“.
Step 4: Recognize that โˆซโ‚€โด ๐“(4 โ€• ๐“) d๐“ is equivalent to the given integral โˆซโ‚€โด 3๐“(4 โ€• ๐“) d๐“ divided by 3, since the integrand in the given integral is scaled by a factor of 3. Therefore, โˆซโ‚€โด ๐“(4 โ€• ๐“) d๐“ = 32 / 3.
Step 5: Substitute โˆซโ‚€โด ๐“(4 โ€• ๐“) d๐“ = 32 / 3 into the expression -6 โˆซโ‚€โด ๐“(4 โ€• ๐“) d๐“ to find the value of the integral. Simplify the expression to complete the solution.

๋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:
2m
๋„์›€์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 Integrals

A definite integral represents the signed area under a curve between two specified limits. It is denoted as โˆซโ‚แต‡ f(x) dx, where 'a' and 'b' are the lower and upper limits, respectively. The value of a definite integral can be interpreted as the accumulation of quantities, such as area, over the interval [a, b]. Understanding this concept is crucial for evaluating integrals and applying properties related to limits.
์ถ”์ฒœ ์˜์ƒ:
๊ฐ€์ด๋“œ ์ฝ”์Šค
05:43
Definition of the Definite Integral

Properties of Integrals

The properties of integrals, such as linearity, additivity, and the reversal of limits, are essential for simplifying and evaluating integrals. For instance, the linearity property states that โˆซ(c * f(x)) dx = c * โˆซf(x) dx for a constant 'c'. Additionally, the property of reversing limits states that โˆซโ‚แต‡ f(x) dx = -โˆซแต‡โ‚ f(x) dx. These properties allow for manipulation of integrals to facilitate easier computation.
์ถ”์ฒœ ์˜์ƒ:

Substitution in Integrals

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

Sigma notation Evaluate the following expressions.                                                                                                                                          

(c)     4                                                                                                                                                                               

       โˆ‘ ฮบยฒ                                                                                                                                                                          

       ฮบ=1                         

๊ต๊ณผ์„œ ์งˆ๋ฌธ

Properties of integrals Suppose โˆซโ‚€ยณฦ’(๐“) d๐“ = 2 , โˆซโ‚ƒโถฦ’(๐“) d๐“ = โ€•5 , and โˆซโ‚ƒโถg(๐“) d๐“ = 1. Evaluate the following integrals.

(c) โˆซโ‚ƒโถ (3ฦ’(๐“) โ€• g(๐“)) 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.

(c) For an increasing or decreasing nonconstant function on an interval [a,b] and a given value of n, the value of the midpoint Riemann sum always lies between the values of the left and right Riemann sums.

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๊ต๊ณผ์„œ ์งˆ๋ฌธ

Sigma notation Express the following sums using sigma notation. (Answers are not unique.)

(c) 1ยฒ + 2ยฒ + 3ยฒ + 4ยฒ

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๊ต๊ณผ์„œ ์งˆ๋ฌธ

Working with area functions Consider the function ฦ’ and the points a, b, and c.

(c) Evaluate A(b) and A(c). Interpret the results using the graphs of part (b) .

ฦ’(๐“) = โ€• 12๐“ (๐“โ€•1) (๐“โ€• 2) ; a = 0 , b = 1 , c = 2

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๊ต๊ณผ์„œ ์งˆ๋ฌธ

Approximating areas Estimate the area of the region bounded by the graph of ฦ’(๐“) = xยฒ + 2 and the x-axis on [0, 2] in the following ways.

(c) Divide [0, 2] into n = 4 subintervals and approximate the area of the region using a right Riemann sum. Illustrate the solution geometrically.

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