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Ch. 5 - Integration
5์žฅ, ๋ฌธ์ œ 5.2.67

Use geometry and properties of integrals to evaluate


โˆซโ‚€ยน (2๐“ + โˆš(1โ€•๐“ยฒ) + 1) d๐“

๊ฒ€์ฆ๋œ ๋‹จ๊ณ„๋ณ„ ์•ˆ๋‚ด
1
Step 1: Break the integral into separate terms using the property of integrals: โˆซโ‚แต‡ [f(๐“) + g(๐“) + h(๐“)] d๐“ = โˆซโ‚แต‡ f(๐“) d๐“ + โˆซโ‚แต‡ g(๐“) d๐“ + โˆซโ‚แต‡ h(๐“) d๐“. This gives โˆซโ‚€ยน (2๐“ + โˆš(1โ€•๐“ยฒ) + 1) d๐“ = โˆซโ‚€ยน 2๐“ d๐“ + โˆซโ‚€ยน โˆš(1โ€•๐“ยฒ) d๐“ + โˆซโ‚€ยน 1 d๐“.
Step 2: Evaluate โˆซโ‚€ยน 2๐“ d๐“. Use the power rule for integration: โˆซ ๐“โฟ d๐“ = (๐“โฟโบยน)/(n+1) + C. Here, n = 1, so โˆซ 2๐“ d๐“ = 2 * (๐“ยฒ/2) = ๐“ยฒ. Apply the limits of integration from 0 to 1.
Step 3: Evaluate โˆซโ‚€ยน โˆš(1โ€•๐“ยฒ) d๐“. Recognize that โˆš(1โ€•๐“ยฒ) represents the equation of a semicircle with radius 1 centered at the origin. The integral โˆซโ‚€ยน โˆš(1โ€•๐“ยฒ) d๐“ calculates the area of one-quarter of the circle. Use the formula for the area of a circle, A = ฯ€rยฒ, and divide by 4.
Step 4: Evaluate โˆซโ‚€ยน 1 d๐“. The integral of a constant c over [a, b] is given by c(bโ€•a). Here, c = 1, a = 0, and b = 1, so โˆซโ‚€ยน 1 d๐“ = 1 * (1โ€•0).
Step 5: Combine the results from Steps 2, 3, and 4. Add the values obtained for โˆซโ‚€ยน 2๐“ d๐“, โˆซโ‚€ยน โˆš(1โ€•๐“ยฒ) d๐“, and โˆซโ‚€ยน 1 d๐“ to get the final result of the integral.

๋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

์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 points on the x-axis. It is denoted as โˆซ_a^b f(x) dx, where 'a' and 'b' are the limits of integration. The value of a definite integral can be interpreted geometrically as the accumulation of the area between the function f(x) and the x-axis from x = a to x = b.
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๊ฐ€์ด๋“œ ์ฝ”์Šค
05:43
Definition of the Definite Integral

Properties of Integrals

Properties of integrals, such as linearity, allow us to break down complex integrals into simpler parts. For example, โˆซ(f(x) + g(x)) dx = โˆซf(x) dx + โˆซg(x) dx. This property is particularly useful when evaluating integrals that consist of multiple terms, as it enables the evaluation of each term separately.
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Geometric Interpretation of Functions

Understanding the geometric interpretation of functions is crucial for evaluating integrals. For instance, the term โˆš(1 - xยฒ) represents a semicircle with radius 1. Recognizing the shapes formed by the functions involved can simplify the evaluation of the integral by allowing the use of geometric area formulas instead of purely algebraic methods.
์ถ”์ฒœ ์˜์ƒ:
04:18
Geometric Sequences - Recursive Formula
๊ด€๋ จ ์‹ค์ฒœ
๊ต๊ณผ์„œ ์งˆ๋ฌธ

Indefinite integrals Use a change of variables or Table 5.6 to evaluate the following indefinite integrals. Check your work by differentiating.                                                                                  

                                                                                                                                                                    

 โˆซ sin ๐“ secโธ ๐“ d๐“

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๊ต๊ณผ์„œ ์งˆ๋ฌธ

Definite integrals Use a change of variables or Table 5.6 to evaluate the following definite integrals.                                                                                                                         

                                                                                                                                                                              

 โˆซโ‚€ยน 2eยฒหฃ d๐“

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๊ต๊ณผ์„œ ์งˆ๋ฌธ

Definite integrals Use a change of variables or Table 5.6 to evaluate the following definite integrals.                                                                                                                         

                                                                                                                                                                              

 โˆซโ‚€แต‰ยฒ (ln p)/p dp

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๊ต๊ณผ์„œ ์งˆ๋ฌธ

Average height of a wave The surface of a water wave is described by y = 5 (1 + cos ๐“) , for โ€• ฯ€ โ‰ค ๐“ โ‰ค ฯ€, where y = 0 corresponds to a trough of the wave (see figure). Find the average height of the wave above the trough on [ โ€•ฯ€ , ฯ€] .

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๊ต๊ณผ์„œ ์งˆ๋ฌธ

Areas of regions Find the area of the region bounded by the graph of ฦ’ and the ๐“-axis on the given interval.


ฦ’(๐“) = ๐“ยณ โ€• 1 on [โ€•1, 2]

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๊ต๊ณผ์„œ ์งˆ๋ฌธ

Cubic zero net area Consider the graph of the cubic y = ๐“ (๐“โ€• a) (๐“โ€• b), where 0 < a < b. Verify that the graph bounds a region above the ๐“-axis, for 0 < ๐“ < a , and bounds a region below the ๐“-axis, for a < ๐“ < b. What is the relationship between a and b if the areas of these two regions are equal? 

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