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Sequences-and-series/186780: Deanna received an e-mail asking her to forward it to 10 other people. Assume that no one breaks the chain and that there are no duplicate recipients. How many e-mails will have been sent after 8 generations, including Deanna's?
Could you do this problem? Thank you for your help. 1 solutions
Answer 140003 by josmiceli(9698) on 2009-03-15 15:16:14 (Show Source):
You can put this solution on YOUR website!The problem says that the 1st generation of
e-mail senders is Deanna, who receives one
sends emails to 10 other people
So far I have:
generation# --- emails sent
--- 1 --------------1
--- 2 --------------10
So far, 11 people have gotten emails
Now each of the 10 people send 10 emails
and 
So far I have:
generation# --- emails sent
--- 1 --------------1
--- 2 --------------10
--- 3 --------------100
So far 111 people have gotten emails
Now, there are 100 people who are going to send
emails to 10 other people.

So far I have:
generation# --- emails sent
--- 1 --------------1
--- 2 --------------10
--- 3 --------------100
--- 4 --------------1000
So far, 1111 people have gotten emails
If I carry this process to 8 generations, the 8th is:
generation# --- emails sent
--- 8 --------------10000000
and the total number of people who have gotten emails is
11,111,111
|
Equations/186634: This question is from textbook mathematical analysis
a new television depreciates $120 per year, and it is worth $340 after four years. find a function that describes the value of this television, if x is the age of the television in years.
In full details please, thank you 1 solutions
Answer 139924 by josmiceli(9698) on 2009-03-14 17:30:55 (Show Source):
You can put this solution on YOUR website!Let  = the original value of the TV
given:
 = depreciation/1 year
You have to understand that depreciation
is what the TV loses in value each year,
so every year it's worth less, and then it
gets depreciated again
------------------------------------------
 is the value of the TV after 1 year
 is the value of the TV after 2 years
 is the value of the TV after 3 years
 is the value of the TV after 4 years
The problem says the TV is worth $340 after 4 years, so

So, the TV was originally worth $820
------------------------------------
Now I need to write a function that tells me the
value of the TV for any given year
If  is the year after purchase,
and  is the value of the TV that year

A quick check is:
What is the TV worth after 4 years?
That's what it should be
|
Distributive-associative-commutative-properties/186662: This question is from textbook Algebra 1
I need help understanding how to find the greatest common factor and factoring it out of a equation.
e.x. 6y^4 + 14y^3 - 10y^2 1 solutions
Answer 139923 by josmiceli(9698) on 2009-03-14 17:07:48 (Show Source):
You can put this solution on YOUR website!The limitation on picking out a common factor
is lowest power of a symbol (x,y z, etc), or
it must be the greatest common divisor of
the numbers that are common to each term

The common symbols are:
 ,  , and 
The lowest power is  , so I can
factor out

For the numbers, the greatest common divisor is 
so I can factor out a
|
Geometry_Word_Problems/186614: How many different triangles can have sides of length 8 and 11 if the third side must have a length which is an integer? 1 solutions
Answer 139888 by josmiceli(9698) on 2009-03-14 07:47:37 (Show Source):
You can put this solution on YOUR website!If I lay the  side down flat, I see that sides
equal to  and  will add up to the 
side, and will not be a triangle, So I must go higher than 
for the 3rd side
I can have:
 and
 and
 and
 and  (this is isosceles)
 and
 and 
.
.
.
 and 
The next one,  and  is like the
 and  , because it lays down flat
on top of the  side, because 
so, the possible integer sides for the 3rd side are:
4 through 18.
|
Age_Word_Problems/186598: This question is from textbook Algebra Structure and Method Book I
A man is three times as old as his son was at the time when the father was twice as old as the son will be in two years from now. Find the present age of each person if the sum of their ages is fifty-five years. 1 solutions
Answer 139880 by josmiceli(9698) on 2009-03-14 00:27:19 (Show Source):
You can put this solution on YOUR website!Let  = Father's age now
Let  = Son's age now
given:

The Son's age in 2 years is

When the Father was twice as old as the Son will be in two years is

How old was the Son then?
The difference in their ages is a constant

The Father's present age is three time the Son's at that time

(1) 
also,
(2) 
(3) 
Substitute (3) in (1)
(1) 
(1) 
(1) 
Multiply both sides of (2) by  and
subtract (1) from (2)
(2) 
(1) 
(3) 
(3) 
and, since
(2) 
(2) 
(2) 
The father is 39 now, and the Son is 16
----------------------------------------
check answer:
The Son's age in 2 years is

When the Father was twice as old as the Son will be in two years is

How old was the Son then?
The difference in their ages is a constant

The Father's present age is three time the Son's at that time

(1) 
(1) 
(1) 
(1) 
(1) 
(1) 
and
(3) 
(3) 
OK
|
Length-and-distance/186465: Two perpendicular lines intersect at point (9,2). If the x-intercept of one line is double the x-intercept of the other, find the possible sum(s) of these x- intercepts. 1 solutions
Answer 139827 by josmiceli(9698) on 2009-03-13 15:25:01 (Show Source):
|
Exponential-and-logarithmic-functions/186562: This question is from textbook
The problem directions state: Solve the equation. Check for extraneous solutions.
49.) 2ln(-x)+7= 14
I understand you remove 7 from both sides, but I am wondering how I change this particular problem into exponential form and what is the set-up for exponential form! Thanks! 1 solutions
Answer 139818 by josmiceli(9698) on 2009-03-13 12:05:56 (Show Source):
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Length-and-distance/186467: A straight line is drawn through the point (3,4). the line cuts the axes at the points A and B such that the area of the triangle OAB is 24. Find the x-intercepts of all such lines 1 solutions
Answer 139784 by josmiceli(9698) on 2009-03-13 04:51:04 (Show Source):
|
Equations/186495: Hello.
I'm needing some help with checking what I did wrong on this problem:
Perform the indicated operation and simplify
(s+t)(s^2-st+t^2)
thanks! 1 solutions
Answer 139779 by josmiceli(9698) on 2009-03-13 00:47:56 (Show Source):
|
Quadratic_Equations/186469: A fraternity charters a bus for a ski trip at a cost of $360. When 6 more students join the trip, each person's cost decreases by $2. How many students were in the original group of ravelers? 1 solutions
Answer 139741 by josmiceli(9698) on 2009-03-12 17:44:45 (Show Source):
You can put this solution on YOUR website!Let  = number of student in original group
Let  = the original cost per person
given:
(1) 
(2) 
(2) 
Substitute (1) in (2)
(2) 
(2) 
(2) 
Substitute this in (1)
(1) 
(1) 
(1) 
Use quadratic formula

There were 30 students in the original group
check:
(1) 
(1) 
(1) 
and
(2) 
(2) 
(2) 
(2) 
OK
|
Exponents/186458: Could someone help me with this problem:
(2/3)^-2(4/5)^-1
I am suppose to write it in simplest form without negative exponents.
I am usually good in algebra but since I got a new math teacher I feel I dont grasp anything anymore :( 1 solutions
Answer 139740 by josmiceli(9698) on 2009-03-12 17:23:52 (Show Source):
You can put this solution on YOUR website!
If you don't get negative exponents, just think of them
like this:
10^4 = 10000
10^3 = 1000
10^2 = 100
10^1 = 10
10^0 = 1
10^-1 = .1
10^-2 = .01
10^-3 = .001
10^-4 = .0001
In general,

Now you just invert each fraction
 answer
|
Systems-of-equations/186409: y=3x and x + y=2
answer: 1/2, 3/2
wanted to know how my book got these fractions as answer need full break down 1 solutions
Answer 139711 by josmiceli(9698) on 2009-03-12 11:28:03 (Show Source):
You can put this solution on YOUR website!(1)  and
(2) 
There are 2 equations and 2 unknowns. Whenever the
number of unknowns matches the number of equations,
then a solution is possible.
First, subtract  from both sides of (1)
(1) 
(1) 
Now simply add (1) and (2)
(1) 
(2) 
(3) 
(3) 
To find  , substitute  in (1)
(1) 
(1) 
(1) 
The solution is  and
|
Travel_Word_Problems/186407: From a point on a straight road, john and fred ride bicycles in opposite directions. john rides 5 miles per hour and fred rides 14 miles per hour. in how many hours will they be 57 miles apart? 1 solutions
Answer 139709 by josmiceli(9698) on 2009-03-12 11:18:21 (Show Source):
|
Linear-systems/186418: An Airplane flew for 4 hours against headwind of 40 km/h. On the
return flight the same wind was now a tail wind, and the flight took 3
hours. Find the speed of the airplane in still air 1 solutions
Answer 139708 by josmiceli(9698) on 2009-03-12 11:12:19 (Show Source):
You can put this solution on YOUR website!Let  = speed of plane in still air
Let  = distance travelled one way
given:
 (against wind)
 (with wind)
Since both are equal to  , set them
equal to eachother

The speed of plane in still air is 280 mi/hr
check:

-------------------

OK
|
Mixture_Word_Problems/186415: a merchant has coffee worth $20 a pound that she wishes to mix with 80 pounds of coffee worth $90 a pound to get a mixture that can be sold for $60 a pound. how many pounds of the $20 coffee should be used? 1 solutions
Answer 139706 by josmiceli(9698) on 2009-03-12 11:01:40 (Show Source):
You can put this solution on YOUR website!Let  = pounds of $20 coffee used
given:
 = cost in dollars of $20 coffee used
 = cost in dollars of $90 coffee used
 = pounds of coffee in final mixture
 = cost in dollars of final mixture
-------------------

60 pounds of $20 coffee must be used
check:

OK
|
Evaluation_Word_Problems/186343: Please help me quickly, I am trying to help my daughter with her homework.
Problem:
At a concert, main floor seats sell for $25.00 and Upper Level seats sell for $12.00. There were 50,000 people in attendance and the concert total ticket sales is $1,112,000. How many main floor seats and upper level seats were sold? 1 solutions
Answer 139675 by josmiceli(9698) on 2009-03-11 23:02:20 (Show Source):
You can put this solution on YOUR website!Let  = number of main floor tickets sold
Let  = number of upper level tickets sold
given:
(1) 
(2) 
There are 2 equations and 2 unknowns. When the
number of equations matches the number of unknowns,
it is solvable.
Multiply both sides of (1) by 
and subtract from (2)
(2) 
(1) 
(3) 
(3)  (rounded off)
and
(1) 
(1) 
(1)  (rounded off)
39,385 mainfloor seats were sold and 10615 upper level
seats were sold
check answer:
(2) 
(2) 
(2) 
(2)  (close enough)
and
(1) 
(1) 
(1) 
OK
|
Mixture_Word_Problems/186265: a tea shop sells grea tea for $4.00 a pound and a white tea for $2.75 per pound. the manager decides to combine the two types of teas to make a mix that sells for $3.50 per pound. the mis should not cause any change in revenue. how much of each tea should combine to make a 10 pound mixture 1 solutions
Answer 139616 by josmiceli(9698) on 2009-03-11 17:45:53 (Show Source):
You can put this solution on YOUR website!Let  = pounds of green tea needed
Let  = pounds of white tea needed
given:
(1)  lb
 dollars
(2) 
Multiply both sides of (1) by  and
subtract (2) from (1)
(1) 
(2) 
(3) 
(3) 
and
(1) 
(1) 
(1) 
4 pounds of white tea and 6 pounds of green tea are needed
|
Linear-systems/186085: This question is from textbook Algebra 1
How do you solve this linear system with substitution?
8x+3y=0
-x-9y=92
All I have got to is...
x=-9y-92
3y(-9y-92)=0
-6y-92=0
-6y=92
I dont think I did it right?? 1 solutions
Answer 139526 by josmiceli(9698) on 2009-03-10 19:46:08 (Show Source):
You can put this solution on YOUR website!(1) 
(2) 
Subtract  from both sides of (1)
(1) 
Divide both sides by 
(1) 
Multiply the right side by 
(1) 
Substitute this in (2)
(2) 
(2) 
(2) 
(2) 
(2) 
And, from
(1) 
(1) 
(1) 
(1) 
check answers:
(1) 
(1) 
OK
(2) 
(2) 
(2) 
OK
|
Numbers_Word_Problems/186080: This question is from textbook Holt Algebra 1
The sum of Anji's age and Carol's age is 66. Carol's age is 2 more than 3 times Anji's age. How old are Carol and Anji? 1 solutions
Answer 139524 by josmiceli(9698) on 2009-03-10 18:49:14 (Show Source):
You can put this solution on YOUR website!Let  = Anji's age
Let  = Carol's age
given:
(1) 
(2) 
Subtract  from both sides of (2)
(2) 
Subtract (2) from (1)
(1) 
(2) 
(3) 
(3) 
and, since
(1) 
(1) 
(1) 
Anji's age is 16, and Carol's age is 50
check:
(2) 
(2) 
(2) 
(2) 
OK
|
Miscellaneous_Word_Problems/186070: Pietro's Pizza and Sandwiches delivered lots of sandwiches one rainy Saturday. They took orders for 30 sandwiches with cheese, 25 with tomatoes, and 18 with pepperoni. there were 18 with cheese and tomato, 14 with tomato and pepperoni, and 10 with all three toppings. there were 8 with only cheese. how many sandwiches did they deliver?
i have worked with the numbers and the pizzas don't add up. i don't know if it is extra info. 1 solutions
Answer 139523 by josmiceli(9698) on 2009-03-10 18:32:23 (Show Source):
You can put this solution on YOUR website!I come up with  sandwiches
I drew 3 interlocking circles with
an area in the middle common to
all three
Here's the breakdowns:
c only ---t only ---p only --- c&t --- t&p --- c&p
-----------------------------------------------------
----8--------3-------0--------18--------14------14
I add up:
8 c only
8 c&t only
3 t only
4 t&p only
0 p only
4 p&c only
10 All 3 toppings
-----
37
|
Polynomials-and-rational-expressions/186066: please help me with this polynomial.
z^2+9z+20
thank you and please show work so i know how to complete it on my own. 1 solutions
Answer 139522 by josmiceli(9698) on 2009-03-10 17:56:38 (Show Source):
You can put this solution on YOUR website!This can be done by the method
known as
-completing the square-
Take  of the coefficient of
the  term, square it, then
add the results to both sides
-------------------------------

But first, I have to get the constant
term on the other side. Subtract 
from both sides

Now complete the square

With this method, the left side always ends up
being a perfect square. In this problem, both
sides are a perfect square

Now take the square root of both sides,
both the (+) and (-) square root

and
 and  are the roots of the polynomial
To factor  ,

and

The factoring is:
|
Graphs/185934: Soybean meal in 16% protein; cornmeal is 8% protein. How many pounds of each should be mixed together in order to get 320-lb mixture that is 10% protein? 1 solutions
Answer 139446 by josmiceli(9698) on 2009-03-10 00:02:58 (Show Source):
You can put this solution on YOUR website!Let  = pounds of soybean meal needed
Let  = pounds of cornmeal needed
given:
 = pounds of protein in soybean meal needed
 = pounds of protein in cornmeal needed
 = pounds of final mixture
--------------
(1) 
(2) 
Multiply both sides of (1) by 
(1) 
(1) 
Multiply both sides of (2) by 
(2) 
Subtract (2) from (1)
(1) 
(2) 
(3) 
(3) 
and
(2) 
(2) 
(2) 
80 pounds of soybean meal and 240 pounds of cornmeal
are needed
check:
(1) 
(1) 
(1) 
(1) 
OK
|
|