Skip to main content
Ch. 5 - Integration
5์žฅ, ๋ฌธ์ œ 5.4.53a

Average value with a parameter Consider the function ฦ’(๐“) = a๐“ (1โ€•๐“) on the interval [0, 1], where a is a positive real number.
(a) Find the average value of ฦ’ as a function of a .

๊ฒ€์ฆ๋œ ๋‹จ๊ณ„๋ณ„ ์•ˆ๋‚ด
1
Step 1: Recall the formula for the average value of a function ฦ’(๐“) on the interval [a, b], which is given by: 1(b-a)fxdx. In this case, the interval is [0, 1] and the function is ฦ’(๐“) = a๐“(1 - ๐“).
Step 2: Substitute the interval [0, 1] and the function ฦ’(๐“) = a๐“(1 - ๐“) into the formula for average value: 110^1(ax(1-x))dx. This simplifies to: 0^1ax(1-x)dx.
Step 3: Expand the integrand a๐“(1 - ๐“) to simplify the integral. This becomes: a(x-x2). The integral now looks like: a0^1(x-x2)dx.
Step 4: Break the integral into two separate parts: a(0^1xdx-0^1x2dx). Compute each integral separately: 0^1xdx and 0^1x2dx. Use the power rule for integration: xndx=xn+1n+1.
Step 5: After computing the integrals, combine the results and multiply by the constant 'a' to find the average value of ฦ’(๐“) as a function of 'a'. The final expression will represent the average value of the function over the interval [0, 1].

๋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.

Average Value of a Function

The average value of a continuous function ฦ’ over an interval [a, b] is calculated using the formula (1/(b-a)) * โˆซ[a to b] ฦ’(x) dx. This concept is essential for determining how the function behaves on the specified interval, providing a single representative value that summarizes the function's overall trend.
์ถ”์ฒœ ์˜์ƒ:

Definite Integral

A definite integral represents the accumulation of quantities, such as area under a curve, over a specific interval. In this context, it is used to compute the integral of the function ฦ’(x) = a๐“(1 - ๐“) from 0 to 1, which is necessary for finding the average value of the function.
์ถ”์ฒœ ์˜์ƒ:
๊ฐ€์ด๋“œ ์ฝ”์Šค
05:43
Definition of the Definite Integral

Parameter in Functions

A parameter is a variable that influences the behavior of a function but is not the primary variable of interest. In this case, 'a' is a parameter that affects the shape and scale of the function ฦ’(x) = a๐“(1 - ๐“), and understanding its role is crucial for expressing the average value as a function of 'a'.
์ถ”์ฒœ ์˜์ƒ:
05:59
Eliminating the Parameter
๊ด€๋ จ ์‹ค์ฒœ
๊ต๊ณผ์„œ ์งˆ๋ฌธ

{Use of Tech} Approximating definite integrals with a calculator Consider the following definite integrals.

(a) Write the left and right Riemann sums in sigma notation for an arbitrary value of n.


โˆซโ‚€ยน cos โปยน ๐“ d๐“

57
views
๊ต๊ณผ์„œ ์งˆ๋ฌธ

Properties of integrals Consider two functions ฦ’ and g on [1,6] such that โˆซโ‚โถฦ’(๐“) d๐“ = 10 and โˆซโ‚โถg(๐“) d๐“ = 5, โˆซโ‚„โถฦ’(๐“) d๐“ = 5 , and โˆซโ‚โดg(๐“) d๐“ = 2. Evaluate the following integrals.


(a) โˆซโ‚โด 3f(๐“) d๐“

61
views
๊ต๊ณผ์„œ ์งˆ๋ฌธ

The velocity in ft/s of an object moving along a line is given by v = ฦ’(t) on the interval 0 โ‰ค t โ‰ค 8 (see figure), where t is measured in seconds.

a) Divide the interval [0,8] into n = 2 subintervals, [0,4] and [4,8]. On each subinterval, assume the object moves at a constant velocity equal to the value of v evaluated at the midpoint of the subinterval, and use these approximations to estimate the displacement of the object on [0,8] (see part (a) of the figure)                                                                                                             


89
views
๊ต๊ณผ์„œ ์งˆ๋ฌธ

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

(a) Find the area function A (๐“) = โˆซโ‚หฃ ฦ’(t) dt using the Fundamental Theorem.

ฦ’(๐“) = cos ๐“ ; a = 0 , b = ฯ€/2 , c = ฯ€

38
views
๊ต๊ณผ์„œ ์งˆ๋ฌธ

Mass from density A thin 10-cm rod is made of an alloy whose density varies along its length according to the function shown in the figure. Assume density is measured in units of g/cm. In Chapter 6, we show that the mass of the rod is the area under the density curve.

(a) Find the mass of the left half of the rod (0 โ‰ค x โ‰ค 5) .

63
views
๊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.

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

47
views