Assignment 16

Here is assignment 16. Let me know what i need to do next or when i should get started on it/have it completed by. I will be out of town for up and coming weekend beginning on friday and i'll be gone till Sunday (when both VHCC and Emory and Henry's spring break begin). Also, i am pretty sure i am submitting the assignment's the correct way but let me know if I am not. Thanks for your help!

ˮ޻ʩ assignment #016 gmk۟ͯEwұҚR Calculus I 03-05-2006

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22:24:21 Problem 5.4.3 (was 5.4.2) fn piecewise linear from (0,1)-(1,1)-(3,-1)-(5,-1)-(6,1). F ' = f, F(0) = 0. Find F(b) for b = 1, 2, 3, 4, 5, 6.What are your values of F(b) for b = 1, 2, 3, 4, 5, 6 and how did you obtain them.

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RESPONSE --> f(1)= 1 f(2)=1.5 f(3)= 1 f(4)= 0 f(5) = -1 f(6) = -1.5

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22:24:43 ** f(x) is the 'rate function'. The change in the 'amount function' F(x) is represented as the accumulated area under the graph of f(x). Since F(0) = 0, F(x) will just the equal to the accumulated area.

We can represent the graph of f(x) as a trapezoidal approximation graph, with uniform width 1.

The first trapezoid extends from x = 0 to x = 1 and has altitude y = 1 at both ends. Therefore its average altitude is 1 and its what is 1, giving area 1. So the accumulated area through the first trapezoid is 1. Thus F(1) = 1.

The second trapezoid has area .5, since its altitudes 1 and 0 average to .5 and imply area .5. The cumulative area through the second trapezoid is therefore still 1 + .5 = 1.5. Thus F(2) = 1.5.

The third trapezoid has altitudes 0 and -1 so its average altitude is -.5 and width 1, giving it 'area' -.5. The accumulated area through the third trapezoid is therefore 1 + .5 - .5 = 1. Thus F(3) = 1.

The fourth trapezoid has uniform altitude -1 and width 1, giving it 'area' -1. The accumulated area through the fourth trapezoid is therefore 1 + .5 - .5 - 1 = 0. Thus F(4) = 0.

The fifth trapezoid has uniform altitude -1 and width 1, giving it 'area' -1. The accumulated area through the fifth trapezoid is therefore 1 + .5 - .5 - 1 - 1 = -1. Thus F(5) = -1.

The sixth trapezoid has altitudes 1 and -1 so its average altitude, and therefore it's area, is 0. Accumulated area through the sixth trapezoid is therefore 1 + .5 - .5 - 1 - 1 + 0 = -1. Thus F(6) = -1. **

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RESPONSE --> i simply analyzed the areas under the curve

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22:26:31 If you made a trapezoidal graph of this function what would be the area of teach trapezoid, and what would be the accumulated area from x = 0 to x = b for b = 1, 2, 3, 4, 5, 6? What does your answer have to do with this question?

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RESPONSE --> it would be the sum of all of the rectangles.

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22:30:35 Problem 5.4.27 (was 5.4.12). integral of e^(x^2) from -1 to 1.

How do you know that the integral of this function from 0 to 1 lies between 0 and 3?

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RESPONSE --> this integral is positive (2.93 to be exact). It is actually a parabola. It is symmetric around the Y axis. Therefore 2 times the integral value of one side (i.e. from 0 to 1) will give you the correct answer for the entire integral problem

You can't find the exact value of this integral, and you can't find an antiderivative.

I assume that 2.93 is calculator output, and while calculator output can be useful it never proves anything and cannot be used to justify your answer on a problem of this nature.

Your observation of symmetry is good and useful.

Note on terminology: A parabola is a very specific conic section, the graph of a specific type of quadratic form, and has unchanging concavity. Among other things e^(x^2) has changing concavity; it is in any case not a parabola. Any parabola can be rotated so its axis of symmetry becomes positive, and in that orientation its graph always represents the graph of a quadratic (2d-degree) polynomial.

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22:31:02 ** The max value of the function is e, about 2.71828, which occurs at x = 1. Thus e^(x^2) is always less than 3.

On the interval from 0 to 1 the curve therefore lies above the x axis and below the line y = 3. The area of this interval below the y = 3 line is 3. So the integral is less than 3.

Alternatively e^(x^2) is never as great as 3, so its average value is less than 3. Therefore its integral, which is average value * length of interval, is less that 3 * 1 = 3. **

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RESPONSE --> ok

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22:33:18 5.4.42. If the average value of v(x) on 1 <= x <= 6 is 4, and the average value on 6 <= x <= 8 is 5, then what is the average value of v(x) on the interval 1 <= x <= 8?

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RESPONSE --> 4.8? I am not quite sure as to the answer of this problem

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22:35:35 The average value of a function over an interval is equal to its integral over that interval, divided by the length of the interval.

To find the average value of v(x) on the interval 1 <= x <= 8 we first find its integral over that interval.

The integral of v(x) from x = 1 to x = 8 is the sum of its integral from x = 1 to x = 6, and its integral from x = 6 to x = 8.

Since the average value of v(x) on the first of these intervals is 4, its integral over that interval is equal to 4 times the length of the interval, or 4 * 5 = 20.

Since the average value of v(x) on the second interval is 5, its integral over that interval is equal to 5 times the length of the interval, or 5 * 2 = 10.

Thus the integral of v(x) from x = 1 to x = 8 is 20 * 10 = 30. The length of the interval being 8 - 1 = 7, the average value is 30 / 7 = 4 2/7, approximately 4.3.

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RESPONSE --> i understand, i overcomplicated the problem by far

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22:36:06 Query Add comments on any surprises or insights you experienced as a result of this assignment.

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RESPONSE --> the problems for this section were tough in the book however i very clearly understand the theorem's and concepts of this section.

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You appear to understand the essential concepts in this chapter. When you get into the actual queries for your course, be sure to document your thinking completely, and be sure to self-critique.