Assignment 10

course Mth 158

\…Ò`ͤȱÈ\Áª²“íñÑÊùGß[Òassignment #010

Your work has been received. Please scroll through the document to see any inserted notes (inserted at the appropriate place in the document, in boldface) and a note at the end. The note at the end of the file will confirm that the file has been reviewed; be sure to read that note. If there is no note at the end, notify the instructor through the Submit Work form, and include the date of the posting to your access page.

010. `query 10

College Algebra

06-14-2007

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15:04:11

1.1.20 (was 1.1.12). Explain, step by step, how you solved the equation 5y + 6 = -18 - y

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RESPONSE -->

First I added y to both sides 6y + 6 = -18. then subtracted 6 from both sides 6y = -24, then divided by 6 and got y= - 4.

confidence assessment: 2

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15:04:44

** STUDENT SOLUTION WITH INSTRUCTOR COMMENT: 5y + 6 = 18 - y

Subtract 6 from both sides, giving us

5y = 12 - y

Add y to both sides,

5y + y = 12 or 6y = 12

divide both sides by 6

y = 2

INSTRUCTOR COMMENT: This is correct for equation 5y + 6 = 18 - y but the equation as I note it is 5y + 6 = -18 - y.

If that's the correct equation the solution is found by practically the same steps but you end up with y = -4. **

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RESPONSE -->

I got it right.

self critique assessment: 3

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15:10:26

1.1.44 (was 1.1.30). Explain, step by step, how you solved the equation (2x+1) / 3 + 16 = 3x

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RESPONSE -->

I first added 16 to both sides (2x +1)/ 3 = 3x - 16. Then to get rid of the fraction I multiplied both sides by 3 and got 2x + 1 = 3(3x - 16).Next I distributed the 3, that gave me 2x + 1 = 9x -48. Then I subtracted 2x from both sides. 1 = 7x - 48, next I added 48 to both sides 49 = 7x, divided by 7 and found x = 7

confidence assessment: 3

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15:11:14

** STUDENT SOLUTION:

(2x + 1) / 3 + 16 = 3x

First, multiply both sides of the equation by 3

2x +1 + 48 =9x or 2x + 49 = 9x

subtract 2x from both sides.

49 = 7x

Divide both sides by 7

7 = x

**

......!!!!!!!!...................................

RESPONSE -->

I did the steps in a diferent order, but still arrived at the correct solution.

self critique assessment: 3

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15:21:25

was 1.1.36. Explain, step by step, how you solved the equation (x+2)(x-3) = (x+3)^2

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RESPONSE -->

First, I multiplied the two binomials together. I distributed x to the second set and got x^2 - 3x. Then distributed 2 and got 2x - 6. Then I put the two together and got x^2 - 3x + 2x - 6, combined like terms to find x^2 -x - 6.Then I sqared ( x + 3) and got x^2 + 3x + 3x+ 9, combined like terms and got x^2+6x + 9 = x^2 - x - 6. Next I added 6 to both sides and got x^2 + 6x + 15 = x^2 - x. Then I added x to both sides and got x^2 + 7x + 15 = x^2. Next I subtracted x^2 from both sides 7x + 15 = 0. Then I subtracted 15 from both sides 7x = -15 divided by 7 and found x to be -15/ 7.

confidence assessment: 1

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15:22:04

** STUDENT SOLUTION: (x+2)(x+3) = (x+3)^2

First, we use the distributive property to remove the parenthesis and get

x^2 - x - 6 = x^2 + 6x + 9

subtract x^2 from both sides,

-x - 6 = 6x + 9

Subtract 9 from both sides

- x - 6 - 9 = 6x or -x - 15 = 6x

add x to both sides

-15 = 7x

Divide both sides by 7

-15/7 = x

**

......!!!!!!!!...................................

RESPONSE -->

That what I did.

self critique assessment: 3

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15:27:04

1.1.52 (was 1.1.48). Explain, step by step, how you solved the equation x / (x^2-9) + 4 / (x+3) = 3 / (x^2-9)/

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RESPONSE -->

I factored (x^2 - 9) into (x + 3)(x - 3). To get a common denominator I multiplied 4 / (x + 3) by ( x- 3) to get 4x- 12/ ( x+3)(x - 3). Then I used the equation x + 4x - 12 = 3 to find x. I added x+ 4x = 5x. 5x - 12 = 3, added 12 to both sides 5x = 15 divided by 5 and x = 3.

confidence assessment: 2

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15:28:15

** Starting with

x / (x^2 -9) + 4 / (x+3) = 3 / (x^2 -9), first factor x^2 - 9 to get

x / ( (x-3)(x+3) ) + 4 / (x+3) = 3 / ( (x-3)(x+3) ).

Multiply both sides by the common denominator ( (x-3)(x+3) ):

( (x-3)(x+3) ) * x / ( (x-3)(x+3) ) + ( (x-3)(x+3) ) * 4 / (x+3) = ( (x-3)(x+3) ) * 3 / ( (x-3)(x+3) ). Simplify:

x + 4(x-3) = 3. Simplify

x + 4x - 12 = 3

5x = 15

x = 3.

If there is a solution to the original equation it is x = 3. However x = 3 results in denominator 0 when substituted into the original equation, and division by 0 is undefined. So there is no solution to the equation.

When you multiplied both sides by x-3, if x = 3 you were multiplying by zero, which invalidated your solution **

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RESPONSE -->

I found x= 3, but I didn't think about it making the denominator 0. I know that I denominator of 0 is undefined.

self critique assessment: 2

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15:33:58

1.1.58 (was 1.1.54). Explain, step by step, how you solved the equation (8w + 5) / (10w - 7) = (4w - 3) / (5w + 7)

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RESPONSE -->

I set both numerators equal to one another. 8w + 5 = 4w - 3. Subtracted 4w from both sides and got 4w+5= -3, then subtracted 5 from both sides and got 4w = -8, divided by 4 and got w= -2. When I set the denominators equal to each other 10w - 7 = 5w + 7 and subtracted 5w from both sides I got 5w - 7 = 7, added 7 to both sides 5w = 14, divided by 5 and got w= 5/14. So w= - 2 and 5/14

confidence assessment: 2

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15:36:13

** STUDENT SOLUTION:

1) clear the equation of fractions by multiplying both sides by the LCM (10w - 7)(5W + 7)

After cancellation the left side reads:

(5w+7)(8w + 5)

After cancellation the right side reads:

(10w - 7)(4w - 3)

multiply the factors on each side using the DISTRIBUTIVE LAW

Left side becomes: (40w^2) + 81w + 35

Right side becomes: (40w^2) - 58w + 21

3) subtract 40w^2 from both sides

add 58w to both sides

subtract 35 from both sides

Rewrite: 139w = - 14 Now divide both sides by 139 to get w = - (14 / 139)

DER**

......!!!!!!!!...................................

RESPONSE -->

I did that one wrong I didn't use LCM I understand how to get LCM and how to use it in this problem. I can see how you used the distributive property to find the equation and how you found the solution.

self critique assessment: 2

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15:38:38

1.1.70 (was 1.1.78). Explain, step by step, how you solved the equation 1 - a x = b, a <> 0.

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RESPONSE -->

I first subtracted 1 from both sides -ax = b -1. then divided by -a to get x = (b - 1) / -a

confidence assessment: 1

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15:40:28

** Start with

1 -ax = b, a <> 0.

Adding -1 to both sides we get

1 - ax - 1 = b - 1, which we simplify to get

-ax = b - 1.

Divide both sides by -a, which gives you

x = (b - 1) / (-a). Multiply the right-hand side by -1 / -1 to get

x = (-b + 1) / a or

x = (1 - b) / a. **

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RESPONSE -->

I didn't multiply the right side by -1. Why did you?

self critique assessment: 2

Generally you want to avoid a negative in the denominator.

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15:43:07

1.1.82 (was 1.1.90). Explain, step by step, how you solved the equation v = g t + v0 for t.

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RESPONSE -->

v0 = 0 because any number* 0 = 0, so I re-wrote the problem as v = gt then divied by g to get v/g = t.

confidence assessment: 1

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......!!!!!!!!...................................

15:44:14

** NOTE: v0 stands for v with subscript 0; the whole expression v0 stands for the name of a variable. It doesn't mean v * 0.

Starting with v = g t + v0, add -v0 to both sides to get

v - v0 = gt. Divide both sides by g to get

(v - v0) / g = t

}or

t = (v - v0) / g. **

......!!!!!!!!...................................

RESPONSE -->

I thought that v0 meant v* 0. I understans that it is a subscript. I understand how you solved the problem for the correct answer.

self critique assessment: 2

.................................................

......!!!!!!!!...................................

15:45:16

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

......!!!!!!!!...................................

RESPONSE -->

It suprised me that I remember how to solve basic equations, its been awhile since I had done that.

confidence assessment: 3

.................................................

"

Keep up the excellent work.

Assignment 10

course Mth 158

\…Ò`ͤȱÈ\Áª²“íñÑÊùGß[Òassignment #010

Your work has been received. Please scroll through the document to see any inserted notes (inserted at the appropriate place in the document, in boldface) and a note at the end. The note at the end of the file will confirm that the file has been reviewed; be sure to read that note. If there is no note at the end, notify the instructor through the Submit Work form, and include the date of the posting to your access page.

010. `query 10

College Algebra

06-14-2007

......!!!!!!!!...................................

15:04:11

1.1.20 (was 1.1.12). Explain, step by step, how you solved the equation 5y + 6 = -18 - y

......!!!!!!!!...................................

RESPONSE -->

First I added y to both sides 6y + 6 = -18. then subtracted 6 from both sides 6y = -24, then divided by 6 and got y= - 4.

confidence assessment: 2

.................................................

......!!!!!!!!...................................

15:04:44

** STUDENT SOLUTION WITH INSTRUCTOR COMMENT: 5y + 6 = 18 - y

Subtract 6 from both sides, giving us

5y = 12 - y

Add y to both sides,

5y + y = 12 or 6y = 12

divide both sides by 6

y = 2

INSTRUCTOR COMMENT: This is correct for equation 5y + 6 = 18 - y but the equation as I note it is 5y + 6 = -18 - y.

If that's the correct equation the solution is found by practically the same steps but you end up with y = -4. **

......!!!!!!!!...................................

RESPONSE -->

I got it right.

self critique assessment: 3

.................................................

......!!!!!!!!...................................

15:10:26

1.1.44 (was 1.1.30). Explain, step by step, how you solved the equation (2x+1) / 3 + 16 = 3x

......!!!!!!!!...................................

RESPONSE -->

I first added 16 to both sides (2x +1)/ 3 = 3x - 16. Then to get rid of the fraction I multiplied both sides by 3 and got 2x + 1 = 3(3x - 16).Next I distributed the 3, that gave me 2x + 1 = 9x -48. Then I subtracted 2x from both sides. 1 = 7x - 48, next I added 48 to both sides 49 = 7x, divided by 7 and found x = 7

confidence assessment: 3

.................................................

......!!!!!!!!...................................

15:11:14

** STUDENT SOLUTION:

(2x + 1) / 3 + 16 = 3x

First, multiply both sides of the equation by 3

2x +1 + 48 =9x or 2x + 49 = 9x

subtract 2x from both sides.

49 = 7x

Divide both sides by 7

7 = x

**

......!!!!!!!!...................................

RESPONSE -->

I did the steps in a diferent order, but still arrived at the correct solution.

self critique assessment: 3

.................................................

......!!!!!!!!...................................

15:21:25

was 1.1.36. Explain, step by step, how you solved the equation (x+2)(x-3) = (x+3)^2

......!!!!!!!!...................................

RESPONSE -->

First, I multiplied the two binomials together. I distributed x to the second set and got x^2 - 3x. Then distributed 2 and got 2x - 6. Then I put the two together and got x^2 - 3x + 2x - 6, combined like terms to find x^2 -x - 6.Then I sqared ( x + 3) and got x^2 + 3x + 3x+ 9, combined like terms and got x^2+6x + 9 = x^2 - x - 6. Next I added 6 to both sides and got x^2 + 6x + 15 = x^2 - x. Then I added x to both sides and got x^2 + 7x + 15 = x^2. Next I subtracted x^2 from both sides 7x + 15 = 0. Then I subtracted 15 from both sides 7x = -15 divided by 7 and found x to be -15/ 7.

confidence assessment: 1

.................................................

......!!!!!!!!...................................

15:22:04

** STUDENT SOLUTION: (x+2)(x+3) = (x+3)^2

First, we use the distributive property to remove the parenthesis and get

x^2 - x - 6 = x^2 + 6x + 9

subtract x^2 from both sides,

-x - 6 = 6x + 9

Subtract 9 from both sides

- x - 6 - 9 = 6x or -x - 15 = 6x

add x to both sides

-15 = 7x

Divide both sides by 7

-15/7 = x

**

......!!!!!!!!...................................

RESPONSE -->

That what I did.

self critique assessment: 3

.................................................

......!!!!!!!!...................................

15:27:04

1.1.52 (was 1.1.48). Explain, step by step, how you solved the equation x / (x^2-9) + 4 / (x+3) = 3 / (x^2-9)/

......!!!!!!!!...................................

RESPONSE -->

I factored (x^2 - 9) into (x + 3)(x - 3). To get a common denominator I multiplied 4 / (x + 3) by ( x- 3) to get 4x- 12/ ( x+3)(x - 3). Then I used the equation x + 4x - 12 = 3 to find x. I added x+ 4x = 5x. 5x - 12 = 3, added 12 to both sides 5x = 15 divided by 5 and x = 3.

confidence assessment: 2

.................................................

......!!!!!!!!...................................

15:28:15

** Starting with

x / (x^2 -9) + 4 / (x+3) = 3 / (x^2 -9), first factor x^2 - 9 to get

x / ( (x-3)(x+3) ) + 4 / (x+3) = 3 / ( (x-3)(x+3) ).

Multiply both sides by the common denominator ( (x-3)(x+3) ):

( (x-3)(x+3) ) * x / ( (x-3)(x+3) ) + ( (x-3)(x+3) ) * 4 / (x+3) = ( (x-3)(x+3) ) * 3 / ( (x-3)(x+3) ). Simplify:

x + 4(x-3) = 3. Simplify

x + 4x - 12 = 3

5x = 15

x = 3.

If there is a solution to the original equation it is x = 3. However x = 3 results in denominator 0 when substituted into the original equation, and division by 0 is undefined. So there is no solution to the equation.

When you multiplied both sides by x-3, if x = 3 you were multiplying by zero, which invalidated your solution **

......!!!!!!!!...................................

RESPONSE -->

I found x= 3, but I didn't think about it making the denominator 0. I know that I denominator of 0 is undefined.

self critique assessment: 2

.................................................

......!!!!!!!!...................................

15:33:58

1.1.58 (was 1.1.54). Explain, step by step, how you solved the equation (8w + 5) / (10w - 7) = (4w - 3) / (5w + 7)

......!!!!!!!!...................................

RESPONSE -->

I set both numerators equal to one another. 8w + 5 = 4w - 3. Subtracted 4w from both sides and got 4w+5= -3, then subtracted 5 from both sides and got 4w = -8, divided by 4 and got w= -2. When I set the denominators equal to each other 10w - 7 = 5w + 7 and subtracted 5w from both sides I got 5w - 7 = 7, added 7 to both sides 5w = 14, divided by 5 and got w= 5/14. So w= - 2 and 5/14

confidence assessment: 2

.................................................

......!!!!!!!!...................................

15:36:13

** STUDENT SOLUTION:

1) clear the equation of fractions by multiplying both sides by the LCM (10w - 7)(5W + 7)

After cancellation the left side reads:

(5w+7)(8w + 5)

After cancellation the right side reads:

(10w - 7)(4w - 3)

multiply the factors on each side using the DISTRIBUTIVE LAW

Left side becomes: (40w^2) + 81w + 35

Right side becomes: (40w^2) - 58w + 21

3) subtract 40w^2 from both sides

add 58w to both sides

subtract 35 from both sides

Rewrite: 139w = - 14 Now divide both sides by 139 to get w = - (14 / 139)

DER**

......!!!!!!!!...................................

RESPONSE -->

I did that one wrong I didn't use LCM I understand how to get LCM and how to use it in this problem. I can see how you used the distributive property to find the equation and how you found the solution.

self critique assessment: 2

.................................................

......!!!!!!!!...................................

15:38:38

1.1.70 (was 1.1.78). Explain, step by step, how you solved the equation 1 - a x = b, a <> 0.

......!!!!!!!!...................................

RESPONSE -->

I first subtracted 1 from both sides -ax = b -1. then divided by -a to get x = (b - 1) / -a

confidence assessment: 1

.................................................

......!!!!!!!!...................................

15:40:28

** Start with

1 -ax = b, a <> 0.

Adding -1 to both sides we get

1 - ax - 1 = b - 1, which we simplify to get

-ax = b - 1.

Divide both sides by -a, which gives you

x = (b - 1) / (-a). Multiply the right-hand side by -1 / -1 to get

x = (-b + 1) / a or

x = (1 - b) / a. **

......!!!!!!!!...................................

RESPONSE -->

I didn't multiply the right side by -1. Why did you?

self critique assessment: 2

Generally you want to avoid a negative in the denominator.

.................................................

......!!!!!!!!...................................

15:43:07

1.1.82 (was 1.1.90). Explain, step by step, how you solved the equation v = g t + v0 for t.

......!!!!!!!!...................................

RESPONSE -->

v0 = 0 because any number* 0 = 0, so I re-wrote the problem as v = gt then divied by g to get v/g = t.

confidence assessment: 1

.................................................

......!!!!!!!!...................................

15:44:14

** NOTE: v0 stands for v with subscript 0; the whole expression v0 stands for the name of a variable. It doesn't mean v * 0.

Starting with v = g t + v0, add -v0 to both sides to get

v - v0 = gt. Divide both sides by g to get

(v - v0) / g = t

}or

t = (v - v0) / g. **

......!!!!!!!!...................................

RESPONSE -->

I thought that v0 meant v* 0. I understans that it is a subscript. I understand how you solved the problem for the correct answer.

self critique assessment: 2

.................................................

......!!!!!!!!...................................

15:45:16

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

......!!!!!!!!...................................

RESPONSE -->

It suprised me that I remember how to solve basic equations, its been awhile since I had done that.

confidence assessment: 3

.................................................

"

Keep up the excellent work.