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Ch. 5 - Integration
5์žฅ, ๋ฌธ์ œ 5.3.111a

Zero net area Consider the function ฦ’(๐“) = ๐“ยฒ โ€• 4๐“ .
(a) Graph ฦ’ on the interval ๐“ โ‰ฅ 0.

๊ฒ€์ฆ๋œ ๋‹จ๊ณ„๋ณ„ ์•ˆ๋‚ด
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Step 1: Start by analyzing the given function ฦ’(๐“) = ๐“ยฒ - 4๐“. Identify its key features, such as the degree of the polynomial (quadratic) and the leading coefficient (positive, indicating the parabola opens upwards).
Step 2: Find the critical points of the function by taking its derivative. Compute ฦ’'(๐“) = d/d๐“ [๐“ยฒ - 4๐“] = 2๐“ - 4. Set ฦ’'(๐“) = 0 to solve for ๐“, which gives the critical points.
Step 3: Determine the vertex of the parabola. The vertex occurs at ๐“ = -b/(2a) for a quadratic function in the form axยฒ + bx + c. Here, a = 1 and b = -4, so the vertex is at ๐“ = 2. Evaluate ฦ’(2) to find the corresponding y-coordinate of the vertex.
Step 4: Identify the x-intercepts by solving ฦ’(๐“) = 0. Factorize the quadratic equation ๐“ยฒ - 4๐“ = 0 as ๐“(๐“ - 4) = 0, which gives the solutions ๐“ = 0 and ๐“ = 4. These are the points where the graph crosses the x-axis.
Step 5: Plot the graph of ฦ’(๐“) on the interval ๐“ โ‰ฅ 0. Mark the vertex, x-intercepts, and other key points. Sketch the parabola, ensuring it opens upwards and passes through the identified points.

๋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.

Graphing Functions

Graphing functions involves plotting points on a coordinate plane to visualize the relationship between the input (x-values) and output (y-values) of a function. For the function ฦ’(๐“) = ๐“ยฒ - 4๐“, this means calculating y-values for various x-values, particularly within the specified interval x โ‰ฅ 0, and connecting these points to form a continuous curve.
์ถ”์ฒœ ์˜์ƒ:
๊ฐ€์ด๋“œ ์ฝ”์Šค
5:53
Graph of Sine and Cosine Function

Finding Roots

Finding the roots of a function refers to determining the values of x for which the function equals zero. For ฦ’(๐“) = ๐“ยฒ - 4๐“, this involves solving the equation ๐“ยฒ - 4๐“ = 0, which can be factored to find the x-intercepts. These roots are critical for understanding where the graph intersects the x-axis and can indicate changes in the function's behavior.
์ถ”์ฒœ ์˜์ƒ:

Understanding Area Under the Curve

The area under the curve of a function on a given interval can provide insights into the function's behavior, such as net area, which accounts for regions above and below the x-axis. In this case, analyzing the graph of ฦ’(๐“) = ๐“ยฒ - 4๐“ will help determine if the net area is zero, which occurs when the positive and negative areas cancel each other out within the specified interval.
์ถ”์ฒœ ์˜์ƒ:
๊ฐ€์ด๋“œ ์ฝ”์Šค
05:59
Estimating the Area Under a Curve with Right Endpoints & Midpoint
๊ด€๋ จ ์‹ค์ฒœ
๊ต๊ณผ์„œ ์งˆ๋ฌธ

{Use of Tech} Midpoint Riemann sums with a calculator Consider the following definite integrals.

(a) Write the midpoint Riemann sum in sigma notation for an arbitrary value of n.


โˆซโ‚€โด (4๐“โ€• ๐“ยฒ) d๐“

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๊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

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

(a) Consider the linear function ฦ’(๐“) = 2x + 5 and the region bounded by its graph and the x-axis on the interval [3,6]. Suppose the area of this region is approximated using midpoint Riemann sums. Then the approximations give the exact area of the region for any number of subintervals.

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๊ต๊ณผ์„œ ์งˆ๋ฌธ

Approximating displacement The velocity in ft/s of an object moving along a line is given by v = 3tยฒ + 1 on the interval 0 โ‰ค t โ‰ค 4, where t is measured in seconds.

(a) Divide the interval [0,4] into n = 4 subintervals, [0,1] , [1.2] , [2,3] , and [3,4]. On each subinterval, assume the object moves at a constant velocity equal to v evaluated at the midpoint of the subinterval, and use these approximations to estimate the displacement of the object on [0, 4] (see part (a) of the figure)

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๊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“) = sin ๐“ ; a = 0 , b = ฯ€/2 , c = ฯ€

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๊ต๊ณผ์„œ ์งˆ๋ฌธ

Symmetry properties Suppose โˆซโ‚€โด ฦ’(๐“) d๐“ = 10 and โˆซโ‚€โด g(๐“) d๐“ = 20. Furthermore, suppose ฦ’ is an even function and g is an odd function. Evaluate the following integrals.


(c) โˆซโ‚‹โ‚„โด (4ฦ’(๐“) โ€• 3g(๐“))d๐“

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