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answered: 49 problems
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logarithm/236328: Rewrite as an equivalent exponential equation. Do not solve
log10^0.000001 = 6
1 solutions

Answer 173980 by Theo(551) About Me  on 2009-11-08 03:20:13 (Show Source):
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log10^0.000001 = 6

I think you might mean:

log(10,.000001) = -6 ?????

This form looks like after being put through algebra.com formula generator.

This would only be if:

10^(-6) = .000001 which looks like after being put through algebra.com formula generator.

since 10^(-6) is the same as 1/(10^6) which equals 1/1000000 which equals .000001, then I suspect this is what you are looking for.

in general, x^y = z if and only if log(x,z) = y

algebra.com formula generated form of this would look like:

in general, if and only if






Numbers_Word_Problems/236331: N is 80% of P
N to the root of 2 is what percent of P to the root of 2?
1 solutions

Answer 173979 by Theo(551) About Me  on 2009-11-08 03:09:50 (Show Source):
You can put this solution on YOUR website!
n = 80% of p means that:

n = .8*p

take the square root of both sides of this equation and you get:

sqrt(n) = sqrt(.8*p) = sqrt(.8) * sqrt(p)

sqrt(.8) = .894427191 * 100% = 89.4427191%

your answer is:

sqrt(n) = 89.4427191% of sqrt(p)

to confirm, let n = 100

this makes p = 100/.8 = 125

equation of

n = .8*p becomes

100 = .8*125

take sqrt of both sides to get:

sqrt(100) = sqrt(.8*125) = sqrt(.8) * sqrt(125)

this becomes:

10 = .894427191 * 11.18033989

this becomes:

10 = 10

Answer is confirmed.



Travel_Word_Problems/236323: A TRAIN TRAVELS 20 FEET IN IN 1/5 OF A SECOND, AT THE SAME SPEED HOW MANY FEET WILL IT TRAVEL IN 3 SECONDS?
1 solutions

Answer 173978 by Theo(551) About Me  on 2009-11-08 02:54:17 (Show Source):
You can put this solution on YOUR website!
It travels 20 feet in (1/5) of a second.

There are 15 * (1/5) of a second in 3 seconds.

It will travel 15 * 20 = 300 feet.



Finance/236335: 2.) Determine the future values if $5,000 is invested in each of the following situations:


a.) 5 percent for ten years
Begin with $100 - - - > 5 percent for 1 year - - > 105
then with each $1 - - - > 105/100 = 1.05 after 1 year
Then for $5,000 it would be 5,000 * 1.05 after 1 year
and then 5,000 * 1.05 * 1.05 after 2 year
for 10 year investment
it would be 5,000 * (1.05)^10 = $8144.475 Ans
1 solutions

Answer 173977 by MissionPossible(16) About Me  on 2009-11-08 02:48:28 (Show Source):
You can put this solution on YOUR website!
2.) Determine the future values if $5,000 is invested in each of the following situations:
a.) 5 percent for ten years
Begin with $100 - - - > 5 percent for 1 year - - > 105
then with each $1 - - - > 105/100 = 1.05 after 1 year
Then for $5,000 it would be 5,000 * 1.05 after 1 year
and then 5,000 * 1.05 * 1.05 after 2 year
for 10 year investment
it would be 5,000 * (1.05)^10 = $8144.473 Ans


Linear-systems/236336: I was asked to simplify this 4z to the eighth power z to the -6 power y to the -9 power times 5y to the -1 power w to the -7 power times 2w to the 7th power
i have not had math for over 30 years stuck bad. Do you also know of any websites that gives free help and explanation of problems and rules.
Any help greatly appreciated
1 solutions

Answer 173976 by Theo(551) About Me  on 2009-11-08 02:45:13 (Show Source):
You can put this solution on YOUR website!
Here are some good ones.

http://www.wtamu.edu/academic/anns/mps/math/mathlab/col_algebra/index.htm

http://www.purplemath.com/lessons.htm

http://tutorial.math.lamar.edu/Classes/Alg/Alg.aspx

http://www.jamesbrennan.org/algebra/

There's tons of stuff on the internet. Just do a search on "algebra" or "algebra lessons" or "algebra tutorials".

Some are pay sites and some are free. The ones above are free.

Algebra.com also has lessons.

You can scan down their home page using the search word "lessons" and down at the bottom towards the right you should find a link.

Here's a link that will guide you if it works.

http://www.algebra.com/tutors/all-lessons.mpl

There are also video lessons.

If you're going to use algebra.com, then some of the terminology that would be helpful is:

x*y means x multiplied by y
x/y means x divided by y
x^y means x raised to the power of y
root(n,x) means the nth root of x
sqrt(x) means the square root of x
a*(b+d) means do the addition first, then multiply

A couple of rules for exponents might help.

x^y*x^z = x^(y+z) example 3^2*3^3 = 3^(2+3) = 3^5

x^y/x^z = x^(y-z) example 3^5/3^2 = 3^(5-2) = 3^3

(x^y)^z = x^(y*z) example (3^2)^3 = 3^(2*3) = 3^6

x^(n/z) = root(z,x)^n example 3^(6/3) = root(3,3)^6 = root(3,3^6) = 3^2 = 9

x^(1/y) = root(y,x) example 27^(1/3) = root(3,27) = 3

x^(-n) = 1/x^n example 3^(-3) = 1/3^3 = 1/27

x*y*z = x*(y*z) = (x*y)*z = z*(y*x) = y*(z*x) example 1*2*3 = 1*(6) = (2)*3 = 3*(2) = 2*(3) with the terms in parentheses being multiplied first.

Your problem is:

Simplify 4z to the eighth power z to the -6 power y to the -9 power times 5y to the -1 power w to the -7 power times 2w to the 7th power

I had a little trouble understanding it.

This is what I think it is and how to simplify it.

4*z^8*z^(-6)*y^(-9)*5*y^(-1)*w^(-7)*2*w^7

If you put it through the algebra.com formula generator, it will look like this:



4z^8*z^(-6) = 4*z(8-6) = 4*z^2

y^(-9) * 5 * y^(-1) = 5*y^(-9)*y^(-1) = 5*y^(-9-1) = 5*y^(-10)

w^(-7)*2*w^7 = 2*w^(-7)*w^7 = 2*w^(-7+7) = 2*w^0 = 2*1 = 2

Your whole equation should then become:

4z^2*5y^(-10)*2

This can be re-ordered to be:

4*5*2*z^2*y^(-10)

This becomes:

40*z^2*y^(-10)

This becomes:

40z^2/y^10

To prove this is correct, then pick some values for z, y, w, and solve the original equation and solve the final equation. If they match, then the simplification was good.

Let z = 2, y = 3, w = 4

Your final equation of 40z^2/y^10 becomes:

40*(2)^2/3^10 = 160/59049 (from final equation)

Your original equation of
4*z^8*z^(-6)*y^(-9)*5*y^(-1)*w^(-7)*2*w^7 becomes:

4*(2)^8*(2)^(-6)*(3)^(-9)*5*(3)^(-1)*(4)^(-7)*2*(4)^7

This becomes:

1024 * (1/64) * (1/19683) * (5/3) * (1/16384) * 32768

This becomes:

(1024 * 5 * 32768) / (64 * 19683 * 3 * 16384)

This becomes:

(1024 * 5 * 2) / (64 * 19683 * 3)

This becomes:

(16 * 5 * 2) / (19683 * 3)

This becomes:

160 / 59049 (from original equation)

The answers match so the simplification looks good.





Trigonometry-basics/236338: how to find the exact value of sin 225
1 solutions

Answer 173975 by nerdybill(2415) About Me  on 2009-11-08 02:37:53 (Show Source):
You can put this solution on YOUR website!
how to find the exact value of sin 225
.
Looking at the unit circle
sin(225)
is in the third quadrant
225 - 180 = 45
sin(45) mapped to the third quadrant is


logarithm/236324: Radioactive strontium 90Sr has been deposited in a large field by acid rain. If sufficient amounts make their way through the food chain to humans, bone cancer can result. It has been determined that the radioactivity level in the field is 1.7 times the save level S. 90Sr decyas according to the formula
A(t)=Aoe^-0.0239t
where Ao is the amount curretly in the field and t is the time in years. How many years will it take until the field is contaminated.
1 solutions

Answer 173974 by nerdybill(2415) About Me  on 2009-11-08 02:33:03 (Show Source):
You can put this solution on YOUR website!
Radioactive strontium 90Sr has been deposited in a large field by acid rain. If sufficient amounts make their way through the food chain to humans, bone cancer can result. It has been determined that the radioactivity level in the field is 1.7 times the save level S. 90Sr decyas according to the formula
A(t)=Aoe^-0.0239t
I think they want to know when the fields will be safe.
.
A(t)=Aoe^-0.0239t
Let x = initial amount of strontium
then
x/1.7 = A(t)
.
x/1.7 = xe^-0.0239t
1/1.7 = e^-0.0239t
ln(1/1.7) = -0.0239t
ln(1/1.7) /-0.0239 = t
22.2 years = t (years before the strontium decays to safe levels)


Geometry_Word_Problems/236325: A car radiator has a capacity of 8 quarts of coolant which is 20% antifreeze. A mechanic needs to drain part of the radiator fluid and replace it with 100% antifreeze to bring the coolant in the system to 60% antifreeze. How much of the original coolant should be drained and replaced by 100% antifreeze to achieve the desired mix?
1 solutions

Answer 173973 by nerdybill(2415) About Me  on 2009-11-08 00:30:26 (Show Source):
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A car radiator has a capacity of 8 quarts of coolant which is 20% antifreeze. A mechanic needs to drain part of the radiator fluid and replace it with 100% antifreeze to bring the coolant in the system to 60% antifreeze. How much of the original coolant should be drained and replaced by 100% antifreeze to achieve the desired mix?
.
Let x = amount drained and replaced by 100% antifreeze
then
.20(8-x) + x = .60(8)
1.6 - .20x + x = 4.8
1.6 + .80x = 4.8
.80x = 3.2
x = 4 quarts


Geometry_Word_Problems/236108: A cube is painted red and then cut into 1000 identical smaller cubes. How many of these cubes are painted red on at least two faces?
1 solutions

Answer 173972 by Edwin McCravy(2878) About Me  on 2009-11-08 00:05:07 (Show Source):
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We have a 10x10x10 large cube that we are going to cut into 1000 small
1x1x1 cubes.

Only the small cubes cut from the edges of the large cube will have
at least two faces painted red.  All the rest will have either 1 or
0 faces painted red.
 
There are 8 small cubes which have exactly three sides painted. 
These are the 8 small cubes located at the 8 vertices (corners) of 
the big cube.  

So let's say we have counted these 8 with three faces painted red.

There are 12 edges of the big cube.  Each of these 12 edges of
the big cube consists of the edges of 10 small cubes.  But 2 of
these are at a corner of the big cube, and we have already
conted these.  So we only need to count the other 8 cubes along
each of the 12 edges, which have exactly 2 faces painted red.    
  
So that's an additional 12x8 or 96.

So the total is 8 small cubes with exactly three faces painted red
plus 96 cubes with exactly two faces painted red. That's 8+96 = 104.

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

Another way to count them is to start with the 1000 cubes and 
start subtracting.

There are the inner 8x8x8 or 512 small cubes cut from the inside
of the big cube which have no faces painted.

On each of the 6 faces of the big cube there are 8x8 or 64 faces
of small cubes which only have 1 face painted.  So that's
64x6 or 384 small cubes which have 1 face painted.  So subtracting

 1000 small cubes 
- 512 small cubes which have no faces painted red
-----
  488 small cubes which have at least one face painted red.
- 384 small cubes which have exactly one face painted red.  
-----
  104 small cubes with at least two faces painted red.

Edwin


Inequalities/235980: I don't understand how to solve the compound inequality. Any help will be greatly appreciated. Thank you!!
5>-2x+4 or 8< equal to -3x + 4

1 solutions

Answer 173971 by punksnotdead28(4) About Me  on 2009-11-07 23:21:03 (Show Source):
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x>-1/2 or x>or equal to -3/4


Miscellaneous_Word_Problems/236034: Can you please explain this to me? I think the argument is correct, but I'm not 100% and I wouldn't know where to begin explaining why. Thanks so much for your help!!

Hosni gave the following argument that - (a + b) = -a + -b, for all integers a and b. If the argument is correct, supply the missing reasons. If it is incorrect, explain why not.
-(a + b) = (-1)(a + b)
= (-1)a + (-1)b
= -a + -b

1 solutions

Answer 173970 by punksnotdead28(4) About Me  on 2009-11-07 23:18:42 (Show Source):
You can put this solution on YOUR website!
It is correct, but more simplified would be -a - b


Linear-equations/236086: Find the equation of the line that contains the give point and has the given slope P(2,3),m=1/2
1 solutions

Answer 173969 by punksnotdead28(4) About Me  on 2009-11-07 23:13:43 (Show Source):


Miscellaneous_Word_Problems/236319: In a basketball game, Will scored 26 points, consisting only of three-point shots and two-point shots. He made a total of 11 shots. How many shots of each type did he make?
1 solutions

Answer 173968 by punksnotdead28(4) About Me  on 2009-11-07 23:09:12 (Show Source):
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2 point shots: 7
3 point shots: 4


Equations/236314: Solve each equation
2(t-4)= 3-(3t+1)
1 solutions

Answer 173967 by stanbon(25959) About Me  on 2009-11-07 22:44:25 (Show Source):
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Solve each equation
2(t-4)= 3-(3t+1)
2t-8 = 3 -3t - 1
5t = 2+8
5t = 10
t = 2
-----------------
Cheers,
Stan H.


Equations/236315: Solve the equation
9y+5-2y= 2y+5-y+3
1 solutions

Answer 173966 by stanbon(25959) About Me  on 2009-11-07 22:41:48 (Show Source):
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Solve the equation
9y+5-2y= 2y+5-y+3
---
7y + 5 = y + 8
6y = 3
y = 1/2
============
Cheers,
Stan H.


Polynomials-and-rational-expressions/236318: t(3t-1)2nd power
1 solutions

Answer 173965 by stanbon(25959) About Me  on 2009-11-07 22:37:38 (Show Source):
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t(3t-1)2nd power
---
t(9t^2 - 6t + 1)
---
9t^3 - 6t^2 + t
============================================
Cheers,
Stan H.


Travel_Word_Problems/236316: a boat can travel 5 miles downstream in the same length of time it travels 3 miles upstream. if the rate of the current is 3mph, find the speed of the boat in still water.
d=5 ?
r=3mh ?
t=?
so simple yet a little hard......????
1 solutions

Answer 173964 by stanbon(25959) About Me  on 2009-11-07 22:31:51 (Show Source):
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a boat can travel 5 miles downstream in the same length of time it travels 3 miles upstream. if the rate of the current is 3mph, find the speed of the boat in still water.
-------
Downstream DATA:
distance = 5 miles ; rate = b+3 mph ; time = d/r = 5/(b+3) hrs
----------------
Upstream DATA:
distance = 3 miles ; rate = b-3 mph ; time = d/r = 3/(b-3)
=============================================================
Equations:
time up = time down
3/(b-3) = 5/(b+3)
---
3(b+3) = 5(b-3)
3b+9 = 5b-15
2b = 24
b = 12 mph (speed of the boat in still water)
===============================================
Cheers,
Stan H.


Radicals/236317: I do not understand can you help?
Simplify the problem and write answers in exponential form.
3^4 + 2 * 3^4
1 solutions

Answer 173963 by stanbon(25959) About Me  on 2009-11-07 22:21:39 (Show Source):
You can put this solution on YOUR website!
I do not understand can you help?
Simplify the problem and write answers in exponential form.
3^4 + 2 * 3^4
---
(3^4) + 2(3^4)
---
= (3^4)(1 + 2)
---
= (3^4)*3
---
= 3^5
= 243
==========
Cheers,
Stan H.


Travel_Word_Problems/234816: A CAR TRAVELS 540 MILES IN 10 HOURS . HOW FAR WILL IT TRAVEL IN 7 HOURS
1 solutions

Answer 173962 by Alan3354(5863) About Me  on 2009-11-07 21:49:08 (Show Source):
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A CAR TRAVELS 540 MILES IN 10 HOURS . HOW FAR WILL IT TRAVEL IN 7 HOURS
----------
540/10 = 54 mph
54*7 = 378 miles


Miscellaneous_Word_Problems/236077: the wavelength(W) of a radio wave varies inversely as its frequency(F). A wave with a frequency of 200kHz has a length of 252m. What is the length of a wave with a frequency of 900kHz?
1 solutions

Answer 173961 by Alan3354(5863) About Me  on 2009-11-07 21:48:00 (Show Source):
You can put this solution on YOUR website!
the wavelength(W) of a radio wave varies inversely as its frequency(F). A wave with a frequency of 200kHz has a length of 252m. What is the length of a wave with a frequency of 900kHz?
------------------
200*252 = k (a constant)
L*900 = k = 50400
L = 50400/900 = 56 meters
-----------------
-----------------
That's the answer given the data, but it's not correct.
The wavelength in meters is 300/f, f = frequency in Megahertz.
200 KHz = 0.2 MHz
300/0.2 = 1500 meters,
not 252 meters


Parallelograms/236313: Name a triangle
1 solutions

Answer 173960 by Jeff Gordon(22) About Me  on 2009-11-07 21:34:58 (Show Source):
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a right triangle


Linear-equations/236299: how do you solve this
x+y=9
-2x+y=-3

1 solutions

Answer 173959 by rfer(2588) About Me  on 2009-11-07 21:08:35 (Show Source):
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x+y=9, y=-x+9
-2x+y=-3
-2x-x+9=-3
-3x=-12
x=4
-----------------
4+y=9
y=5
---------------
-2*4+5=-3
-8+5=-3


Linear-equations/236085: Find the equation of the line that contains the point (3,2) and is parallel to the graph of 3x+y=-3
1 solutions

Answer 173958 by rfer(2588) About Me  on 2009-11-07 21:01:25 (Show Source):


Linear-equations/236087: find th x- and y- intercepts of the graph of the equation y=2x+8
1 solutions

Answer 173957 by rfer(2588) About Me  on 2009-11-07 20:49:20 (Show Source):
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y=2x+8
y int=(0,8)
x int=(-4,0)


Miscellaneous_Word_Problems/236006: The sum of lisa's age and Ellen's age is 41. five years from now, the sum of their ages will be three times lisa's present age. How old is Lisa?
Also to solve this, it has to be either the substitution or elimination method.
Thanks.
1 solutions

Answer 173956 by ankor@dixie-net.com(6567) About Me  on 2009-11-07 20:47:31 (Show Source):
You can put this solution on YOUR website!
Try the elimination method
:
Write an equation for each statement:
:
"The sum of lisa's age and Ellen's age is 41."
E + L = 41
:
" five years from now, the sum of their ages will be three times lisa's present age."
(E+5) + (L+5) = 3L
E + L + 10 = 3L
E + L - 3L = -10
E - 2L = -10
Subtract this equation from the 1st equation
E + L = 41
E -2L = -10
--------------subtraction eliminates E, find L
3L = 51
L =
L = 17 yrs is Lisa's present age
:
:
Check solution, E = 41 - 17 = 24
"five years from now, the sum of their ages will be three times lisa's present age."
24 + 5 + 17 + 5 = 3(17)
29 + 22 = 51; confirms our solution






Percentage-and-ratio-word-problems/236079: find the ratio of the amount spent for food and the amount spent for rent.
320 FOR FOOD
480 FOR RENT
1 solutions

Answer 173955 by rfer(2588) About Me  on 2009-11-07 20:47:05 (Show Source):


Finance/236074: Convert the decimal number to the given base.
68 to base eight

1 solutions

Answer 173954 by rfer(2588) About Me  on 2009-11-07 20:45:35 (Show Source):
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68=104 base 8


Radicals/236143: i need help solving binomils
1 solutions

Answer 173953 by Jeff Gordon(22) About Me  on 2009-11-07 20:30:10 (Show Source):
You can put this solution on YOUR website!
did you read the example of a bad question?


Linear-equations/236089: Determine whether the line through points p1 and p2 is parallel to, perpendicular to, or neither parallel nor perpendicular to the line through points Q1 and Q2
P1(-1,4),P2(2,5);Q1(2,4),Q2(3,1)
1 solutions

Answer 173952 by rfer(2588) About Me  on 2009-11-07 20:24:09 (Show Source):
You can put this solution on YOUR website!
perpendicular to


Percentage-and-ratio-word-problems/236094: Sam invested part of his 10,000 bonus in a fund that paid an 11% profit and invested the rest in stock that suffered a 4% loss. Find the amount of each investment if his overall net profit was 650?
Please Help
1 solutions

Answer 173951 by rfer(2588) About Me  on 2009-11-07 20:20:25 (Show Source):
You can put this solution on YOUR website!
.11x-.04(10000-x)=650
.11x-400+.04x=650
.15x=1050
x=$7000 at 11%
$3000 at 4%


Linear-equations/236162: Hello,
Having a problem with
5/4x + 1/8x =3/8+x fractions 5 over 4 x + 1 0ver 8x = 3 over 8x
not sure how to do this, fractions are hard for me.
Laurie
1 solutions

Answer 173950 by rfer(2588) About Me  on 2009-11-07 20:11:54 (Show Source):
You can put this solution on YOUR website!
5/4x+1/8x=3/8+x
10/8x+1/8x=3/8+8/8x
3/8x=3/8
x=(3/8)/(3/8)
x=3/8*8/3
x=24/24
x=1