005

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course Mth163

Question: `q001. Note that this assignment has 10 questions

Evaluate the function y = x^2 for x values -3, -2, -1, 0, 1, 2, and 3. What are your y values?

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Your solution:

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9

4

1

0

1

4

9

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confidence rating #$&*: 3

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Given Solution:

You should have obtained y values 9, 4, 1, 0, 1, 4, 9, in that order.

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Self-critique (if necessary):

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Self-critique rating:OK

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Question: `q002. Evaluate the function y = 2^x for x values -3, -2, -1, 0, 1, 2, and 3. What are your y values?

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Your solution:

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1/8

1/4

1/2

1

2

4

8

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confidence rating #$&*:

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Given Solution:

By the laws of exponents, b^-x = 1 / b^x. So for example 2^-2 = 1 / 2^2 = 1/4.

Your y values will be 1/8, 1/4, 1/2, 1, 2, 4 and 8. Note that we have used the fact that for any b, b^0 = 1.

It is a common error to say that 2^0 is 0. Note that this error would interfere with the pattern or progression of the y values.

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Self-critique (if necessary):

ANYTHING, raised to the zero power is always 1, except for zero why is that???

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x^a * x^0 = x^(a + 0) = x^a.

If x^a * x^0 = x^a, then x^0 must be 1.

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Question: `q003. Evaluate the function y = x^-2 for x values -3, -2, -1, 0, 1, 2, and 3. What are your y values?

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Your solution:

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-1/9

-1/4

-1

Infinity

1

1/4

1/9

Why are the ones ones, why aren’t they -1/2 and 1/2 ???

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For example,

1^(-2) = 1 / 1^2 = 1 / 1 = 1.

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confidence rating #$&*: 3

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Given Solution:

By the laws of exponents, x^-p = 1 / x^p. So x^-2 = 1 / x^2, and your x values should be 1/9, 1/4, and 1. Since 1 / 0^2 = 1 / 0 and division by zero is not defined, the x = 0 value is undefined. The last three values will be 1, 1/4, and 1/9.

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Self-critique (if necessary):

When I typed in 0^-2 my calculator told me infinity, why do you think that is???

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Don't expect your calculator to be mathematically accurate. Calculators are designed for consumers, not mathematicians. Many don't even respect the order of operations.

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Self-critique rating:2

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Question: `q004. Evaluate the function y = x^3 for x values -3, -2, -1, 0, 1, 2, and 3. What are your y values?

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Your solution:

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-27

-8

-1

0

1

8

27

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confidence rating #$&*: 3

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Given Solution:

The y values should be -27, -8, -1, 0, 1, 8, 27

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Self-critique (if necessary):

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Self-critique rating:OK

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Question: `q005. Sketch graphs for y = x^2, y = 2^x, y = x^-2 and y = x^3, using the values you obtained in the preceding four problems. Describe the graph of each function.

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Your solution:

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y = x^2 parabola

y = 2^x is higher on the right hand side approaching zero to the left hand side

y = x^-2 graph of a polynomial of degree 3

y = x^3 odd power graph

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confidence rating #$&*:

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Given Solution:

The graph of y = x^2 is a parabola with its vertex at the origin. It is worth noting that the graph is symmetric with respect to the y-axis. That is, the graph to the left of the y-axis is a mirror image of the graph to the right of the y-axis.

The graph of y = 2^x begins at x = -3 with value 1/8, which is relatively close to zero. The graph therefore starts to the left, close to the x-axis. With each succeeding unit of x, with x moving to the right, the y value doubles. This causes the graph to rise more and more quickly as we move from left to right. The graph intercepts the y-axis at y = 1.

The graph of y = x^-2 rises more and more rapidly as we approach the y-axis from the left. It might not be clear from the values obtained here that this progression continues, with the y values increasing beyond bound, but this is the case. This behavior is mirrored on the other side of the y-axis, so that the graph rises as we approach the y-axis from either side. In fact the graph rises without bound as we approach the y-axis from either side. The y-axis is therefore a vertical asymptote for this graph.

The graph of y = x ^ 3 has negative y values whenever x is negative and positive y values whenever x is positive. As we approach x = 0 from the left, through negative x values, the y values increase toward zero, but the rate of increase slows so that the graph actually levels off for an instant at the point (0,0) before beginning to increase again. To the right of x = 0 the graph increases faster and faster.

Be sure to note whether your graph had all these characteristics, and whether your description included these characteristics. Note also any characteristics included in your description that were not included here.

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Self-critique (if necessary):

The graph of y = 2^x begins at x = -3 with value 1/8, the graph goes from left to right.. its growing

The graph of y = x^2 vertex at origin symmetric on both sides

The graph of y = x^-2 acts the same on both sides of x axis therefore has horizontal asymptote

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Self-critique rating:2

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Question: `q006. Make a table for y = x^2 + 3, using x values -3, -2, -1, 0, 1, 2, 3. How do the y values on the table compare to the y values on the table for y = x^2? How does the graph of y = x^2 + 3 compare to the graph of y = x^2?

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Your solution:

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Same parabola that has vertically shifted 3 units up from every y coordinate.

My y values differ by just adding three from the original. Or subtracting 3 from each new y coordinate to obtain original y coordinate values.

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confidence rating #$&*:

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Given Solution:

A list of the y values will include, in order, y = 12, 7, 4, 3, 4, 7, 12.

A list for y = x^2 would include, in order, y = 9, 4, 1, 0, 1, 4, 9.

The values for y = x^2 + 3 are each 3 units greater than those for the function y = x^2.

The graph of y = x^2 + 3 therefore lies 3 units higher at each point than the graph of y = x^2.

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Self-critique (if necessary):

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Self-critique rating:OK

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Question: `q007. Make a table for y = (x -1)^3, using x values -3, -2, -1, 0, 1, 2, 3. How did the values on the table compare to the values on the table for y = x^3? Describe the relationship between the graph of y = (x -1)^3 and y = x^3.

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Your solution:

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New y values

-64

-27

-8

-1

0

1

8

Compared to old y values

-27

-8

-1

0

1

8

27

On my new graph I scaled my y axis my 10s and x axis I counted by ones. So my graphs look a little off my new graph almost looks like a check mark. Old one still looks like an odd power graph (super skinny S or snake)

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confidence rating #$&*: 3

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Given Solution:

The values you obtained should have been -64, -27, -8, -1, 0, 1, 8.

The values for y = x^3 are -27, -8, -1, 0, 1, 8, 27.

The values of y = (x-1)^3 are shifted 1 position to the right relative to the values of y = x^3. The graph of y = (x-1)^3 is similarly shifted 1 unit to the right of the graph of y = x^3.

STUDENT QUESTION

I assumed the graph was shifted 1 unit down since the graph passes through (0, -1) instead of origin. Then again, it passes through (1, 0), so could it be said that the graph is shifted 1 unit down OR 1 unit to the right?

INSTRUCTOR RESPONSE

Based on those two points that would be correct. Nowever, for example, (-2, -8) shifts to (-1, -8), a shift to the right, but not to (-2, -9), as would be the case if this was a downward shift.

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Self-critique (if necessary):

(x-1) shifts one to the right compared to original

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Self-critique rating: 3

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Question: `q008. Make a table for y = 3 * 2^x, using x values -3, -2, -1, 0, 1, 2, 3. How do the values on the table compare to the values on the table for y = 2^x? Describe the relationship between the graph of y = 3 * 2^x and y = 2^x.

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Your solution:

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Vertically shifts 3 so your overall graph is going to get taller and thinner, because your vertex stays the same while everything else moves of an altitude 3 times as much from original y value.

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This is a vertical stretch, not a vertical shift.

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. y=2^x

1/8

1/4

1/2

1

2

4

8

y = 3 * 2^x

3/8

3/4

3/2

3

6

12

24

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confidence rating #$&*:

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Given Solution:

You should have obtained y values 3/8, 3/4, 3/2, 3, 6, 12 and 24.

Comparing these with the values 1/8, 1/4, 1/2, 1, 2, 4, 8 of the function y = 2^x we see that the values are each 3 times as great.

The graph of y = 3 * 2^x has an overall shape similar to that of y = 2^x, but each point lies 3 times as far from the x-axis. It is also worth noting that at every point the graph of y = 3 * 2^x is three times as 'high' as the corresponding point of y = 2^x.

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Self-critique (if necessary):

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Self-critique rating:OK

If you understand the assignment and were able to solve the previously given problems from your worksheets, you should be able to complete most of the following problems quickly and easily. If you experience difficulty with some of these problems, you will be given notes and we will work to resolve difficulties.

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Question: `q009. How do the values on a table for y = (x + 2)^2 compare to those for y = x^2? Use x values -3, -2, -1, 0, 1, 2, 3 to construct each table. What is the axis of symmetry for this function?

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Your solution:

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Your y values will move 2 units horizontally to the left

y = (x + 2)^2 (y values)

1

0

1

4

9

16

25

y = x^2 (y values)

-9

-4

-1

0

1

4

9

The AOS is -b/2(a)

The vertex is the point of symmetry, so the vertex of y = x^2 is (0,0) the vertex of y = (x + 2)^2 is (0,0)

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You didn't include x values in your table.

If you had you would see clearly that (0, 0) is not a point of the graph of y = (x+2)^2.

So that point can't be the vertex.

Sketch that parabola based on your table and see if you can locate the correct vertex.

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confidence rating #$&*:

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Question: `q010. Explain in terms of the values of y = x^2 for the numbers x = -2, -1, 0, 1, 2 why we expect the graph of y = x^2 to be symmetric about the y axis.

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Your solution:

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0^2 = 0 =y, and x=0 so the x and y are both zero is is the midpoint for the reflection of these coordinates

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You can't explain this just in terms of the value at x = 0.

0^3 = 0, but your statements don't apply to the graph of y = x^3.

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confidence rating #$&*:

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Self-critique rating:2

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See if you can revise your answers to thos last two questions according to my notes.

&#Please see my notes and submit a copy of this document with revisions, comments and/or questions, and mark your insertions with &&&& (please mark each insertion at the beginning and at the end).

Be sure to include the entire document, including my notes.

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