Assignment R8

course MTH 158

å­“†ÄÎÐùZÉîÖÔá«ùĉ…ç|„Þassignment #008

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.

008. `query 8

College Algebra

06-17-2008

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

12:19:57

Extra Question: What is the simplified form of sqrt( 4 ( x+4)^2 ) and how did you get this result?

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

RESPONSE -->

The sqrt of 4 is 2, and the sqrt of (x+4)^2 is x+4, so...

2 * | x+4 |

confidence assessment: 2

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

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

12:20:04

** sqrt(a b) = sqrt(a) * sqrt(b) and sqrt(x^2) = | x | (e.g., sqrt( 5^2 ) = sqrt(25) = 5; sqrt( (-5)^2 ) = sqrt(25) = 5. In the former case x = 5 so the result is x but in the latter x = -5 and the result is | x | ).

Using these ideas we get

sqrt( 4 ( x+4)^2 ) = sqrt(4) * sqrt( (x+4)^2 ) = 2 * | x+4 | **

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

RESPONSE -->

ok

self critique assessment: 3

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

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

12:20:30

Extra Question: What is the simplified form of (24)^(1/3) and how did you get this result?

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

RESPONSE -->

The rule for this is a^m/n = ^n sqrt a^m. So...

(24)^(1/3) = cubed root (24)

cubed root (24) = cubed root (8 * 3), which gives us

2 cubrt 3

confidence assessment: 2

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

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

12:20:37

** (24)^(1/3) =

(8 * 3)^(1/3) =

8^(1/3) * 3^(1/3) =

2 * 3^(1/3) **

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

RESPONSE -->

ok

self critique assessment: 3

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

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

12:23:41

Extra Question:. What is the simplified form of (x^2 y)^(1/3) * (125 x^3)^(1/3) / ( 8 x^3 y^4)^(1/3) and how did you get this result?

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

RESPONSE -->

(x^2 y)^(1/3) * (125 x^3)^(1/3) / ( 8 x^3 y^4)^(1/3) =

(x^2/3 * qubrt y) * 5x / 2xy cubrt y which cancels out to

x^2/3 * 5 / 2y

confidence assessment: 2

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

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

12:23:58

** (x^2y)^(1/3) * (125x^3)^(1/3)/ ( 8 x^3y^4)^(1/3)

(x^(2/3)y^(1/3)* (5x)/[ 8^(1/3) * xy(y^(1/3)]

(x^(2/3)(5x) / ( 2 xy)

5( x^(5/3)) / ( 2 xy)

5x(x^(2/3)) / ( 2 xy)

5 ( x^(2/3) ) / (2 y) **

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

RESPONSE -->

ok

self critique assessment: 3

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

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

12:27:28

R.8.28:. What is the simplified form of 2 sqrt(12) - 3 sqrt(27) and how did you get this result?

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

RESPONSE -->

2 sqrt(12) - 3 sqrt(27) =

2 * 2 sqrt(3) - 3 * 3 sqrt(3) =

4 sqrt(3) - 9 sqrt(3) = -5 sqrt(3)

confidence assessment: 2

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

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

12:27:41

** 2* sqrt(12) - 3*sqrt(27) can be written as

2* sqrt (4*3) - 3 * sqrt (9*3) by factoring out the maximum possible perfect square in each square root. This simplifies to

2* sqrt (4) sqrt(3) - 3 * sqrt (9) sqrt(3) =

2*2 sqrt 3 - 3*3 * sqrt 3 =

}

4*sqrt3 - 9 * sqrt3 =

-5sqrt3. **

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

RESPONSE -->

ok

self critique assessment: 3

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

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

12:44:39

Extra Question. What is the simplified form of (2 sqrt(6) + 3) ( 3 sqrt(6)) and how did you get this result?

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

RESPONSE -->

(3 sqrt(6)) * (2 sqrt(6) + 3) =

36 + 9 sqrt(6)

confidence assessment: 2

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

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

12:44:53

** (2*sqrt(6) +3)(3*sqrt(6)) expands by the Distributive Law to give

(2*sqrt(6) * 3sqrt(6) + 3*3sqrt(6)), which we rewrite as

(2*3)(sqrt6*sqrt6) + 9 sqrt(6) =

(6*6) + 9sqrt(6) =

36 +9sqrt(6). **

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

RESPONSE -->

ok

self critique assessment: 3

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

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

12:55:09

Extra Qustion. What do you get when you rationalize the denominator of 5 / sqrt(10) and what steps did you follow to get this result?

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

RESPONSE -->

Multiplying the num and denom by sqrt(10) we get

5 sqrt(10) / 10, which goes down to

sqrt(10) / 2

confidence assessment: 2

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

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

12:55:18

** Starting with 5/sqrt10 we multiply numerator and denominator by sqrt(10) to get

(5*sqrt10)/(sqrt10*sqrt10) =

(5sqrt10)/10 =

sqrt10/2 **

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

RESPONSE -->

ok

self critique assessment: 3

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

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

13:00:16

Extra Question. What do you get when you rationalize the denominator of 10 / (4 - sqrt(2) ) and what steps did you follow to get this result?

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

RESPONSE -->

Multiply the num and denom by (4 + sqrt(2) )

10 (4 + sqrt(2) ) / 16 - 4sqrt(2) + 4sqrt(2) + 2 =

10 (4 + sqrt(2) ) / 18

confidence assessment: 2

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

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

13:03:41

** Starting with

10/(4-sqrt2) multiply both numerator and denominator by 4 + sqrt(2) to get

(10* (4+sqrt2))/ (4-sqrt2)(4+sqrt2). Since (a-b)(a+b) = a^2 - b^2 the denominator is (4+sqrt(2) ) ( 4 - sqrt(2) ) = 16 - 2 = 14 so we have

(40+ 10sqrt2) / 14. Dividing numerator and denominator by 2 we end up with

(20 + 5 sqrt(2) / 7 **

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

RESPONSE -->

understood

self critique assessment: 3

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

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

22:36:13

Extra Question: What steps did you follow to simplify (-8)^(-5/3) and what is your result?

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

RESPONSE -->

The rule for this is a^m/n = ^n sqrt a^m. So...

(-8)^(-5/3) = cubrt (5/8)

confidence assessment: 1

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

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

22:36:58

** (-8)^(-5/3) = [ (-8)^(1/3) ] ^-5. Since -8^(1/3) is -2 we get

[-2]^-5 = 1 / (-2)^5 = -1/32. **

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

RESPONSE -->

ok

self critique assessment: 1

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

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

11:12:30

R.8.62. What steps did you follow to simplify (8/27)^(-2/3) and what is your result?

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

RESPONSE -->

Turn 8/27 into its reciprocal

(8/27)^(-2/3) = (27/8)^(2/3)

Apply the exponent

cubrt (27)^2 / cubrt (8)^2 = cubrt (729) / cubrt (64) =

9/4

confidence assessment: 1

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

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

11:12:51

** Starting with

(8/27)^(-2/3) we can write as

(8^(-2/3)/27^(-2/3)). Writing with positive exponents this becomes

(27^(2/3)/8^(2/3))

27^(2/3) = [ 27^(1/3) ] ^2 = 3^2 = 9 and

8^(2/3) = [ 8^(1/3) ] ^2 = 2^2 = 4 so the result is

(27^(2/3)/8^(2/3)) = 9/4. **

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

RESPONSE -->

ok

self critique assessment: 3

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

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

11:19:19

Extra Question. What steps did you follow to simplify 6^(5/4) / 6^(1/4) and what is your result?

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

RESPONSE -->

6^(5/4) / 6^(1/4) = ^4 root (6)^5 / ^4 root (6)

^4 root of (6)^5 = 6 ^4 root (6), so...

6 ^4 root (6) / ^4 (6) = 6

confidence assessment: 1

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

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

11:19:32

** Use the laws of exponents (mostly x^a / x^b = x^(a-b) as follows:

6^(5/4) / 6^(1/4) =

6^(5/4 - 1/4) =

6^1 =

6. **

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

RESPONSE -->

ok

self critique assessment: 3

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

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

11:22:46

R.9.36. What steps did you follow to simplify (x^3)^(1/6) and what is your result, assuming that x is positive and expressing your result with only positive exponents?

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

RESPONSE -->

(x^3)^(1/6) = x^3/6

x^3/6 = x^1/2

x^1/2 = sqrt (x)

confidence assessment: 1

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

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

11:22:58

** Express radicals as exponents and use the laws of exponents.

(x^3)^(1/6) =

x^(3 * 1/6) =

x^(1/2). **

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

RESPONSE -->

ok

self critique assessment: 3

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

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

11:27:26

Extra Question. What steps did you follow to simplify (x^(1/2) / y^2) ^ 4 * (y^(1/3) / x^(-2/3) ) ^ 3 and what is your result, assuming that x is positive and expressing your result with only positive exponents?

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

RESPONSE -->

(x^(1/2) / y^2) ^ 4 * (y^(1/3) / x^(-2/3) ) ^ 3 =

x^2 / y^8 * x^-6/3 =

x^2 / y^8 * x^-2 =

x^2 / y^8 * 2/x =

2x / y^8

confidence assessment: 1

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

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

11:30:20

** (x^(1/2) / y^2) ^ 4 * (y^(1/3) / x^(-2/3) ) ^ 3 =

x^(1/2 * 4) / y^(2* 4) * y^(1/3 * 3) / x^(-2/3 * 3)=

x^2 / y^8 * y / x^(-2) =

x^2 * x^2 / y^7 =

x^4 / y^7. **

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

RESPONSE -->

Understood - I misread the question and figured it out using (x^(1/2) / y^2) ^ 4 * x^(-2/3) ) ^ 3

rather than

(x^(1/2) / y^2) ^ 4 * (y^(1/3) / x^(-2/3) ) ^ 3

self critique assessment: 2

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

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

12:12:43

R.8.96. Factor 8 x^(1/3) - 4 x^(-2/3), x <> 0.

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

RESPONSE -->

8 x^(1/3) - 4 x^(-2/3) =

cubrt(8x) - cubrt(4x^-2) =

2 cubrt(x) - cubrt [(4)(2/x)]

confidence assessment: 1

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

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

12:18:48

** To factor 8x^(1/3)- 4x^(-2/3) we first need to write the expression without negative exponents. To accomplish this we multiply through by x^(2/3) / x^(2/3), obtaining

(8 x^(1/3 + 2/3) - 4x^(-2/3 + 2/3) / x^(2/3) =

(8 x - 4) / x^(2/3). We then factor 2 out of the numerator to obtain

4 ( 2x - 1) / x^(2/3).

Other correct forms include:

( 4x^(1/3) ) ( 2 - ( 1/x) )

8 x^(1/3) - 4 / x^(2/3). **

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

RESPONSE -->

understood

self critique assessment: 2

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

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

12:18:55

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

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

RESPONSE -->

confidence assessment: 1

................................................."

You appear to be doing very well here. Let me know if you have questions.