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#1 2006-02-19 16:09:14

ineedhelp
Member
Registered: 2006-01-21
Posts: 7

Rational Expressions -- Homework :(

Here's my answers,  please let me know where I went wrong.

1. Find all values of x that make the rational expression undefined:

(xsquared -9)
----------------
(xsquared +13x +36)

Answer:
(x+3) (x-3)
---------------
(x+4) (x-4)

2. Simplify:

4                           
(3r-1 )               
---------------   
4               
-----   +4
(3r-1)

4                         (3r-1) 
-----     -4  times   -------  +4
(3r-1 )                  -4         



12r-4
-------  -16
12r-4


Answer: -15


3. Simplify:

6x to the 8th - 10x to the 6th
----------------------------------
-2x to the 8th

2x to the 6th (3xsquared -5)
----------------------------------
2x to the 8th

Answer: x to the 3rd (3xsquared -5)

4.  The average number of vehicles waiting to pay a toll at the toll booth of a super highway is modeled by the function 

n(x) = xsquared
--------------------
.5(1-x)

where x is a quantity between 0 and 1 known as traffic intensity.  What happens to the average number of vehicles waiting as the value representing the traffic intensity increases? Explain your answer.

  A) The average number of vehicles waiting decreases at first, but then increases.
  B) The average number of vehicles waiting remains constant.
Answer: C) The average number of vehicles waiting increases.
  D) The average number of vehicles waiting decreases.

5. Perform the indicated operation and simplify.

4p-4                  5p-5
------ divided by ------
p                       3psquared


4p-4                3squared
-----   times     -----------
p                     5p-5


3psquared +4p -4
---------------------
5psquared - 5p

Answer:
(3p+2) (3p-2)
----------------
p



I have a feeling I got all of these wrong.  Any help would be greatly appreciated.  Thanks.

Also, how do you all get the complex formula's and exponents and all to show up in the forums?  I can't seem to figure that one out.

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#2 2006-02-20 04:16:59

kempos
Member
Registered: 2006-01-07
Posts: 77

Re: Rational Expressions -- Homework :(

1. Denominator: (x+4)(x+9)

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#3 2006-02-20 04:19:59

kempos
Member
Registered: 2006-01-07
Posts: 77

Re: Rational Expressions -- Homework :(

3. (3x^2-5)/x^2

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