Assignment 16 Query

course pc 163

assignment #016016. `query 16

Precalculus I

10-29-2008

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assignment #016

016. `query 16

Precalculus I

10-29-2008

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13:52:56

`questionNumber 160000

behavior and source of exponential functions problem 1, perversions of laws of exponents

Why is the following erroneous: a^n * b^m = (ab) ^ (n*m)

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RESPONSE -->

When you plug in a^n*b^m=(ab)^(n*m) into numbers the answers are not equal.

confidence assessment: 2

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13:53:04

`questionNumber 160000

STUDENT RESPONSE: my example was (4^2)(5^3) did not equal 20^6

INSTRUCTOR COMMENT

** more generally a^n * b^n = a^(n+m), which usually does not equal (ab) ^ (n * m) **

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RESPONSE -->

I see.

self critique assessment: 2

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13:54:18

`questionNumber 160000

Why is the follow erroneous: a^(-n) = - a^n

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RESPONSE -->

It would be correct if a^(-n)= 1/a^n b/c both are positive but the way it is on the left makes one negative and one positive.

confidence assessment: 2

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13:54:26

`questionNumber 160000

STUDENT RESPONSE: 2^-3 is not equal to -2^3

INSTRUCTOR COMMENT:

** A more general counterexample: a^(-n) = 1 / a^n is positive when a is positive whereas -a^n is negative when a is positive **

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RESPONSE -->

I see.

self critique assessment: 2

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13:54:57

`questionNumber 160000

Why is the following erroneous: a^n + a^m = a^(n+m)

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RESPONSE -->

B/c whe you plug in the numbers the response was not equal.

confidence assessment: 2

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13:55:05

`questionNumber 160000

STUDENT RESPONSE: (5^3)+(5^4) is not equal to 5^7

INSTRUCTOR COMMENT:

(5^3) * (5^4) = (5^7) since (5*5*5) * (5*5*5*5) = 5*5*5*5*5*5*5 = 5^7.

However (5^3) + (5^7) = 5*5*5 + 5*5*5*5*5 = 5*5*5( 1 + 5*5) = 5^3( 1 + 5^2), not 5^7.**

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RESPONSE -->

I understand

self critique assessment: 2

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13:59:48

`questionNumber 160000

STUDENT RESPONSE: Why is the following erroneous: a^0 = 0

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RESPONSE -->

If you plug a number in for a say 5^0 it will not equal 0.

self critique assessment: 2

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13:59:59

`questionNumber 160000

4^0 is not equal to 0

INSTRUCTOR COMMENT:

** a^(-n) * a^n = 0 but neither a^(-n) nor a^n need equal zero **

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RESPONSE -->

I see.

self critique assessment: 2

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14:01:32

`questionNumber 160000

Why is the following erroneous: a^n * a^m = a^(n*m).

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RESPONSE -->

Because 5^8*5^2 doesnt equal %=5^16.

confidence assessment: 2

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14:01:40

`questionNumber 160000

STUDENT RESPONSE: (4^7)(4^2) is not equal to 4^14

INSTRUCTOR COMMENT:

Right. Generally a^n * a^m = a^(n+m), not a^(n*m).

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RESPONSE -->

I see.

self critique assessment: 2

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14:03:50

`questionNumber 160000

problem 2. Graph and describe

Give basic points and asymptote; y values corresponding to the basic points, ratio of these y values: y = 1200 (2^(.12 t) )

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RESPONSE -->

Basic points would be (0, 1200), and (1, 1304) it would be in negative x axis

and the ratio wold approx. be 1.78

confidence assessment: 2

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14:04:00

`questionNumber 160000

STUDENT RESPONSE

(0,1200),(1,1304)

negative x-axis

ratio=163/150

INSTRUCTOR COMMENT:

the precise ratio is 2^.12, which is probably pretty close to 163/150

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RESPONSE -->

i see

self critique assessment: 2

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14:05:01

`questionNumber 160000

give basic points and asymptote; y values corresponding to the basic points, ratio of these y values: y = 400 ( 1.07 ) ^ t

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RESPONSE -->

(0,400),(1,428)

It would also be in the negative x axis

and 1.07 would be ratio.

confidence assessment: 2

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&#Very good responses. Let me know if you have questions. &#