Math Is Fun Forum
  Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ • π ƒ -¹ ² ³ °

You are not logged in.

#1 Help Me ! » Rational Expressions -- Homework :( » 2006-02-19 16:09:14

ineedhelp
Replies: 2

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.

#2 Help Me ! » check my homework » 2006-02-11 10:19:42

ineedhelp
Replies: 2

Do five out six, including Q2 and / or Q5. The problems that involve finding a solution (Q2, Q4, Q5) are to be done algebraically - by setting up and solving an equation. The object of Q2, for example, is not to 'play with' various consecutive-integer combinations until coming up with the solution (which is five and six) but to decide what the 'unknown' (x, say) should represent, and: (1) develop an equation that involves the unknown and utilizes the information provided; and then (2) solve that equation algebraically – demonstrating that five and six are a solution by 'plugging in' these values into the equation is not solving it. Please show all work / explain your answers.

1. Factor completely.  64x squared  - 9

I got 8x-9


2. Solve the problem Find two consecutive integers such that the sum of their squares is  61.
No answer.  I have no idea.




3. Factor  15z squared  - 2z  - 8

(-4, 2)

15 (z-4) (z+2)


4. Find an integer solution to the following equation: (5x  - 3) squared  =  18x squared + 1

5x squared -9 = 18x squared +1

-13x squared -10



5. Solve the problem. The printed matter on a  12 by  18 centimeter page of a book must cover  40 square centimeters. If all margins are to be the same width, how wide should the margins be?
No answer.  I have no idea.




6. Factor the trinomial. x squared + 2xy  - 24y squared

(6, -4)

(x+6y) (x-4y)

#3 Help Me ! » a problem at work » 2006-02-06 19:36:34

ineedhelp
Replies: 3

I need help figuring out a percentage increase.  If, over 4 years the sales of all stores are listed below.  The sales at store 1 are to the right. 

Year     Sales at all stores      Sales at Store 1
2002      243                         11 (4.5%)
2003      192                         39 (20.5%)
2004      229                         59 (25.7%)
2005      253                         65 (25.8%)

What is the percentage increase each year?
What is the percentage increase from 02 to 05?
If the trend continues, what percentage increase can we expect in the next 3 years.

#4 Re: Help Me ! » check my homework » 2006-01-28 11:29:12

mathsyperson wrote:

The first answer is fine.

In the second one, the gradients need to be calculated differently.

Between (3, -5) and (-1, 7), there is a gradient of

Similarly, between (6, -13) and (-2, 11), there is a gradient of

They have the same gradient and so are parallel.

I see my mistake. I did 7-5 and -1+3 to get 2/2 and 11-13 and -2+6 to get -2/4. I'll fix it. Thanks.

#5 Help Me ! » check my homework » 2006-01-28 09:05:00

ineedhelp
Replies: 5

I have two homework problems that I'm not sure I got right.  If someone could tell me if my answer is correct that would be great.  If its not right, i'll try to solve it again. 

Suppose the sales of a particular brand of appliance satisfy the relationship: S(x) = 140x + 100 where S(x) represents the number of sales in year x, with x = 0 corresponding to 1982. Find the number of sales in 1987.

S(x) = 140(5) + 100
I came up with Sales in 1987 were 800.

Decide whether the pair of lines is parallel, perpendicular, or neither: the line through (3, -5) and (-1, 7) and the line through the points (6, -13) and (-2,11)

The first line slope is 2/2 and and the second line slope is -2/4. I came up with neither, because the the slope would be the same if parallel or reciprocal if perpendicular.  In this case they are niether.

#6 Re: Help Me ! » Homework help. I don't even know where to start. » 2006-01-21 21:45:32

Dang.  Looks so easy now.  Hard to see why I didn't see it myself.  Thanks for the help.

#7 Help Me ! » Homework help. I don't even know where to start. » 2006-01-21 16:13:42

ineedhelp
Replies: 3

Fantastic Flags, Inc., finds that the cost to make x flags is: C = 19x + 10, 135
while the revenue produced from them is R = 37x (C and R are in dollars).

What is the smallest whole number of flags, x, that must be sold for the company to show a profit (that is, the point at which revenue begins to exceed cost)?

Board footer

Powered by FluxBB