Assignment 25 

course Mth 151

̾Jᶱassignment #025

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025. `query 25

College Algebra

11-17-2007

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assignment #025

025. `query 25

College Algebra

11-17-2007

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15:22:11

query 5.3.12 using prime factors find the greatest common factor of 180 and 300.

What is the greatest common factor and how did you use prime factors to find it?

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RESPONSE -->

180 - 2 * 2 * 3 * 3 * 5

300 - 2 * 2 * 3 * 5 * 5

2*2*3*5 = 60

Used the primes to mutiple out to find the factor

confidence assessment: 2

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15:23:01

** The prime factorizations are 180=2 ^2 * 3 ^ 2 * 5 and 300=2 ^2 * 3 ^1 * 5^2.

They have in commin 2^2, 3 and 5, and no higher power of any of these factors. Since 2^2 * 3^1 * 5^1=60 the greatest common factor is 60. **

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RESPONSE -->

I did not combine the factors in each group. I just left them 2 * 2, etc.

self critique assessment: 2

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15:33:39

query 5.3.24 Euclidean algorithm to find GCF(25,70)

Show how you used the Euclidean algorithm to find the greatest common factor of the two numbers.

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RESPONSE -->

70/25 = 2 w/20 remaining

25/20 = 1 w/5 remaining

20/5 = 4

5 is the greatest common factor

confidence assessment: 2

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15:34:16

** To apply the Euclidean algorithm we divide the larger number by the smaller, obtaining a remainder. We then divide the remainder by the divisor and repeat this process until we get 0 remainder. The greatest common divisor is the last divisor.

In this case 70 divided by 25 gives us remainder 20.

Then we divide the previous divisor 25 by the remainder 20, obtaining remainder 5.

Then we divide the previous divisor, which is now 20, by the remainder 5. The remainder of this division is 0.

So the last divisor, which is 5, is the greatest common factor. **

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RESPONSE -->

That is what I came up with.

self critique assessment: 2

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15:45:14

query 5.3.36 LCM of 24, 36, 48

How did you use the prime factors of the given numbers to find their greatest common factor?

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RESPONSE -->

24 - 2 * 2 * 2 * 3

36 - 2 * 2 * 3 * 3

48 - 2 * 2 * 2 * 2 * 3

2*2*3 = 12

Mutiply the prime factors that all three have in common.

confidence assessment: 2

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15:45:54

** The prime factorizations are 24 = 2*2*2*3, 36 = 2*2*3*3, 48 = 2*2*2*2*3.

The smallest number that includes all these factors has four 2's and two 3's.

2*2*2*2 * 3*3 = 144. So 144 is the GCF. **

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RESPONSE -->

I did the common mutiple instead of the of common factor.

self critique assessment: 2

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15:57:06

query 5.3.48 GCF of 48, 315, 450

Show how you used the Euclidean algorithm to find the greatest common factor of the three given numbers.

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RESPONSE -->

450/315 = 1 w/135 remaining

315/135 = 2 w/45 remianing

135/45 = 3

confidence assessment: 2

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16:03:47

** Applying the Euclidean Algorithm to 315 and 48:

315 divided by 48 gives us remainder 27.

48 divided by 27 gives us remainder 21.

27 divided by 21 gives us remainder 3.

6 divided by 3 gives us remainder 0.

The last divisor is 3, which is therefore the GCF of 315 and 48.

The GCF of the three numbers is therefore the GCF of 450 and 3, which is found by first dividing 450 by 3, which gives us remainder 0.

So the last divisor is 3, which is therefore the GCF of the three numbers. **

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RESPONSE -->

I got stuck but I see what I did. I worked with the 2 largest numbers instead of the 2 smallest. I didn't follow through with the dividing or I would have found that it was 3 instead of 45.

self critique assessment: 2

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16:04:54

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

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RESPONSE -->

I think the Euclidean Algorithm was a little harder to do. As in the last problem I didn't do a step so it messed up the whole answer.

self critique assessment: 2

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I think you understand everything. Be sure you let me know if you have questions.