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josmiceli answered: 9815 problems
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Percentage-and-ratio-word-problems/181455: Valerie's monthly electric bill last year was $125. This year, her monthly electric bill is $150. What is the percent of increase from last year to this year?
1 solutions

Answer 136067 by josmiceli(9817) About Me  on 2009-02-11 00:39:19 (Show Source):
You can put this solution on YOUR website!
The increase is 150+-+125+=+25
The percent increase is:
25%2F125%2A100+=+20%


Miscellaneous_Word_Problems/181456: A grocer sells potatoes in 4pound bags and 3 pound bags. He sold 594 bags of potatoes on Thursday.. He sold the same number of 4 pound bags as he did 3 pound bags. How many of each did he sell ?
1 solutions

Answer 136066 by josmiceli(9817) About Me  on 2009-02-11 00:36:29 (Show Source):
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594%2F2+=+297
He sold 297 of each


Miscellaneous_Word_Problems/181457: The state of Nevada has an area of 286,367 square kilometers. In 2005, Nevada had an estimated population of 2,414,807 people. Approximately how many people per square kilometer is this?
1 solutions

Answer 136065 by josmiceli(9817) About Me  on 2009-02-11 00:34:03 (Show Source):
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2414807+%2F+286367 people/km2
8.43, or about 8 people/km2


Proportions/181454: This question is from textbook
i do not understand scales for pre algebra here is my question:

Actual size:30ft
drawing size: 6 inches
1 solutions

Answer 136064 by josmiceli(9817) About Me  on 2009-02-11 00:29:57 (Show Source):
You can put this solution on YOUR website!
6 in on a map represents 30 ft on the ground
It's like you got into a helicopter and climbed
higher and higher until something on the
ground that was 30 ft long looked 6 in long
If you got even higher, it might look 1/2 in long
All the scale is saying is:
How does 6 in compare with 30 ft?
How many inches are in 30 ft?
30 ft x 12 in/ft = 360 in
The scale is 6 in / 360 in, or
1 in / 60 in
Note that feet and inches are like apples and oranges.
You can't compare them directly


Linear-systems/181450: This question is from textbook Algebra & trigonometry blitzer
as written on my homework =
solve the system :
4x-7/2y=-18
7/2x-3y=-31/2
1 solutions

Answer 136062 by josmiceli(9817) About Me  on 2009-02-10 23:48:00 (Show Source):
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(1) 4x+-+%287%2F2%29y+=+-18
(2) %287%2F2%29x+-+3y+=+-%2831%2F2%29
Multiply both sides of (2) by 8%2F7
(2) %288%2F7%29%287%2F2%29%2Ax+-+%288%2F7%29%2A3y+=+-%288%2F7%29%2831%2F2%29
(2) 4x+-+%2824%2F7%29y+=+-%28124%2F7%29
Subtract (1) from (2)
(2) 4x+-+%2824%2F7%29y+=+-%28124%2F7%29
(1) -4x+%2B+%287%2F2%29y+=+126%2F7
%2849%2F14+-+48%2F14%29%2Ay+=+2%2F7
%281%2F14%29%2Ay+=+2%2F7
y+=+4
Plug this back into (1)
(1) 4x+-+%287%2F2%29y+=+-18
(1) 4x+-+%287%2F2%29%2A4+=+-18
4x+=+-18+%2B+14
4x+=+-4
x+=+-1
The solutions are x+=+-1 and y+=+4


Systems-of-equations/181451: Lorena bought 10 packs of styrofoam cups for the graduation dance. a pack of fifty 12-oz cups costs $1.80 and apack of fifty 16-oz cups costs $2.40. Lorena paid a total of $21.60 excluding tax. How many packs of each size cup did she buy?
1 solutions

Answer 136060 by josmiceli(9817) About Me  on 2009-02-10 23:31:07 (Show Source):
You can put this solution on YOUR website!
Let a = the number of packs of 12 oz cups she bought
Let b = the number of packs of 16 oz cups she bought
given:
(1) a+%2B+b+=+10
(2) 180a+%2B+240b+=+2160
Multiply both sides of (1) by 180 and subtract from (2)
(2) 180a+%2B+240b+=+2160
(1) -180a+-+180b+=+-1800
60b+=+360
b+=+6
and, since
(1) a+%2B+b+=+10
a+%2B+6+=+10
a+=+4
She bought 4 packs of 12 oz cups and
6 packs of 16 oz cups
check answer:
(2) 180a+%2B+240b+=+2160
(2) 180%2A4+%2B+240%2A6+=+2160
720+%2B+1440+=+2160
2160+=+2160
OK


Equations/181245: x^-1/3x^3/4 over x^1/4= here are my choices: 1, x^1/6, x^1/2, or 1/x^1/2
1 solutions

Answer 135904 by josmiceli(9817) About Me  on 2009-02-10 03:24:08 (Show Source):
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%28x%5E%28-%281%2F3%29%29%2Ax%5E%283%2F4%29%29+%2F+x%5E%281%2F4%29


x%5E%28-%281%2F3%29%29%2Ax%5E%283%2F4%29%2Ax%5E%28-%281%2F4%29%29


Following the general rule, x%5Ea%2Ax%5Eb%2Ax%5Ec+=+x%5E%28a%2Bb%2Bc%29,


x%5E%28-%281%2F3%29%29%2Ax%5E%281%2F2%29


x%5E%28-%282%2F6%29%29%2Ax%5E%283%2F6%29


x%5E%281%2F6%29 answer


Travel_Word_Problems/181114: two military squads are 26 miles apart. they plan to rendezvous at some intermediate point. if one squad hikes 2/3 mph faster than the other, and they meet in 3 hrs, what is the rate of the faster squad?
1 solutions

Answer 135791 by josmiceli(9817) About Me  on 2009-02-09 17:00:40 (Show Source):
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Let r = the rate of the slower squad
Let d = the distance the slower squad travels in 3 hrs
given:
The rate of the faster squad is
%28r+%2B+%282%2F3%29%29
The distance the faster squad travels in 3 hrs is
26+-+d
---------------------
For slower squad:
(1) d+=+3r
For faster squad:
26+-+d+=+%28r+%2B+%282%2F3%29%29%2A3
26+-+d+=+3r+%2B+2
(2) d+=+24+-+3r
Subtract (1) from (2)
(2) d+=+24+-+3r
(1) -d+=+-3r
0+=+24+-+6r
6r+=+24
r+=+4 mi/hr
The rate of the faster squad is
r+%2B+%282%2F3%29+=+4.67mi/hr
The faster squad's rate was 4.67 mi/hr
check answer
d+=+3r
d+=+12 mi
26+-+d+=+%28r+%2B+%282%2F3%29%29%2A3
26+-+12+=+%28r+%2B+%282%2F3%29%29%2A3
14++=+3r+%2B+2
3r+=+12
r+=+4 mi/hr
OK


Radicals/181124: sqrt40a^3b^4
It asks that i right the expression in simplest radical form. since 40 and 3 has no sqrt i dnt no where to begin. Thanks for any help.
1 solutions

Answer 135785 by josmiceli(9817) About Me  on 2009-02-09 16:36:34 (Show Source):
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sqrt%2840a%5E3%2Ab%5E4%29
Factor out everything under the square root sign
that is a perfect square
sqrt%284a%5E2%2Ab%5E4%2A10a%29
sqrt%284a%5E2%2Ab%5E4%29%2Asqrt%2810a%29
2a%2Ab%5E2%2Asqrt%2810a%29 answer


Graphs/181052: What is the graph of f(x)= log5x ?
1 solutions

Answer 135735 by josmiceli(9817) About Me  on 2009-02-09 12:13:23 (Show Source):


Equations/181058: Suppose that you are taking a course that has 4 tests. The first three tests are for 100 points each and the fourth test is for 200 points. To get an B in the course, you must have an average of at least 80 percent on the 4 tests. Your scores on the first 3 tests were 83, 75, and 91. What is the minimum score you need on the fourth test to get an B for the course?
1 solutions

Answer 135711 by josmiceli(9817) About Me  on 2009-02-09 10:12:24 (Show Source):
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I'll call the points scored on the tests a, b, c, and d
Points scored on a, b, and c are:
83+%2B+75+%2B+91+=+249
The total possible points for the 4 tests are
3%2A100+%2B+200+=+500
In order to average 80%,
%28249+%2B+d%29%2F500+=+.8
249+%2B+d+=+.8%2A500
d+=+400+-+249
d+=+151
You must score 151 points out of 200 to get a B


Polynomials-and-rational-expressions/181059: I am homeschooled with the School of Tomorrow. I have no teacher, and am struggling with factoring trinomials, particularly coefficients greater than one and complex factoring. Right now I am trying to solve 6X%5E2%2B14X%2B4 Please help me!
1 solutions

Answer 135705 by josmiceli(9817) About Me  on 2009-02-09 10:01:27 (Show Source):
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6x%5E2+%2B+14x+%2B+4
To locate the roots, set the equation equal to 0
6x%5E2+%2B+14x+%2B+4+=+0
Divide both sides by 2
3x%5E2+%2B+7x+%2B+2+=+0
I often try to factor by trying combinations that will
factor the outside terms and try to get the inside term,
for instance:
(3x + ?)(x + ?) I've got the 1st term factored, now for the 3rd
(3x + 2)(x + 1) Does this work?
%283x+%2B+2%29%28x+%2B+1%29+=+3x%5E2+%2B+5x+%2B+2 not quite
How about
(3x + 1)(x + 2) ?
%283x+%2B+1%29%28x+%2B+2%29+=+3x%5E2+%2B+7x+%2B+2 that's it
----------------------
Some are not this neat, and you have to use the quadratic equation
x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
Use this when the form of the equation is
ax%5E2+%2B+bx+%2B+c+=+0
a+=+3
b+=+7
c+=+2
Some are not this neat, and you have to use the quadratic equation
x+=+%28-7+%2B-+sqrt%28+7%5E2-4%2A3%2A2+%29%29%2F%282%2A3%29+
x+=+%28-7+%2B-+sqrt%28+49+-+24+%29%29+%2F+6+
x+=+%28-7+%2B-+sqrt%2825%29+%29+%2F+6+
x+=+%28-7+%2B-+5+%29+%2F+6+
x+=+-%287%2F6%29+%2B+%285%2F6%29
x+=+-%281%2F3%29
%28x+%2B+%281%2F3%29%29+=+0
and
x+=+-%287%2F6%29+-+%285%2F6%29
x+=+-%2812%2F6%29
x+=+-2
%28x+%2B+2%29+=+0
---------------
%28x+%2B+%281%2F3%29%29%28x+%2B+2%29+=+0
x%5E2+%2B+%287%2F3%29x+%2B+%282%2F3%29+=+0
Multiply both sides by 3
3x%5E2+%2B+7x+%2B+2+=+0


Quadratic_Equations/181025: Joe has a collection of nickles and dimes that is worth $6.05. If the number of dimes was doubled and the number of nickles was decreased by 10,the vlue of th ecoins would be $9.85. How many dimes does he have?
1 solutions

Answer 135694 by josmiceli(9817) About Me  on 2009-02-09 00:47:54 (Show Source):
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Let n = the number of nickels
Let d = the number of dimes
given:
10%2A%282d%29+%2B+5%2A%28n+-+10%29+=+985 (in pennies)
20d+%2B+5n+-+50+=+985
(1) 5n+%2B+20d+=+1035
(2) 5n+%2B+10d+=+605
Subtract (2) from (1)
(1) 5n+%2B+20d+=+1035
(2) -5n+-+10d+=+-605
10d+=+430
d+=+43
He has 43 dimes
And, since
(2) 5n+%2B+10d+=+605
5n+%2B+430+=+605
5n+=+175
n+=+35
check answer:
(1) 5n+%2B+20d+=+1035
5%2A35+%2B+20%2A43+=+1035
175+%2B+860+=+1035
1035+=+1035
OK


Finance/181026: This question is from textbook Algebra 1 COncepts and skills
I dont really understand how to find the balance or what the interest is ?
using this formula y = C(1+r)t
1 solutions

Answer 135692 by josmiceli(9817) About Me  on 2009-02-09 00:37:24 (Show Source):
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The formula for interest is:
I+=+C%2Ar%2At where
C = principle
r = the rate
t = time
Example:
You invest $1,000 at an annual interest rate of 3%
After 2 years:
I+=+1000%2A.03%2A2
I+=+60
So, you make $60 in interest after 2 years
--------------------
You got the formula wrong. It should be:
y+=+C%281+%2B+rt%29
To understand, you should factor it.
y+=+C+%2B+Crt
What this says is:
(Principle + Interest) = (Principle) + (Interest)
The C is principle
The Crt is interest
-------------------------
Continuing with the example,
You invest $1,000 at an annual interest rate of 3% for 2 years
y+=+C%281+%2B+rt%29
y+=+1000%281+%2B+.03%2A2%29
y+=+1000%281+%2B+.06%29
y+=+1000%2A1.06
y+=+1060
1060 is what you invested + the interest the money earned
after 2 years at 3%


Word_Problems_With_Coins/180987: This question is from textbook College Algebra
Mary has $4.40 in nickles,dimes and quarters. She has four more dimes than quarters and twice as many nickles as dimes. How many coins of each type does she have?
1 solutions

Answer 135673 by josmiceli(9817) About Me  on 2009-02-08 21:07:05 (Show Source):
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Let n = number of nickels
Let d = number of dimes
Let q = number of quarters
given:
(1) d+=+q+%2B+4
(1) q+=+d+-+4
(2) n+=+2d
(3) 5n+%2B+1d+%2B+25q+=+440 (in cents)
Substitute d-4 in (1) and 2d in (2) for
q and n in (3)
(3) 5%282d%29+%2B+1d+%2B+25%28d+-+4%29+=+440
10d+%2B+d+%2B+25d+-+100+=+440
36d+=+540
d+=+15
and
(1) q+=+d+-+4
q+=+15+-+4
q+=+11
and
(2) n+=+2d
n+=+2%2A15
n+=+30
She has 30 nickels, 15 dimes, and 11 quarters
check:
(3) 5n+%2B+1d+%2B+25q+=+440 (in cents)
5%2A30+%2B+15+%2B+25%2A11+=+440
150+%2B+15+%2B+275+=+440
440+=+440
OK


Quadratic_Equations/180998: 3. Walt made an extra $12,000 last year from a part-time job. He invested part of the money at 7% and the rest at 9%. He made a total of $970 in interest. How much was invested at 7%?
1 solutions

Answer 135672 by josmiceli(9817) About Me  on 2009-02-08 20:51:31 (Show Source):
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Let a = amount invested @ 7%
Let b = amount invested @ 9%
given:
(1) .07a+%2B+.09b+=+970
(2) a+%2B+b+=+12000
Multiply both sides of (2) by .07
and subtract from (1)
(1) .07a+%2B+.09b+=+970
(2) -.07a+-+.07b+=+.07%2A12000
And, subtracting:
(1) .07a+%2B+.09b+=+970
(2) -.07a+-+.07b+=+-840
.02b+=+130
b+=+6500
And, since
(2) a+%2B+b+=+12000
a+=+12000+-+6500
a+=+5500
$5500 was invested @ 7%
check:
(1) .07a+%2B+.09b+=+970
.07%2A5500+%2B+.09%2A6500+=+970
385+%2B+585+=+970
970+=+970
OK


Human-and-algebraic-language/180802: This question is from textbook Beginning Algebra with Applications
A postal clerk sold some $.34 stamps and some $.23 stamps. Altogether, 15 stamps were sold for the total cost of $4.44. How many of each type of stamp were sold?
1 solutions

Answer 135533 by josmiceli(9817) About Me  on 2009-02-07 20:40:15 (Show Source):
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Let the number of $.34 stamps = a
Let the number of $.23 stamps = b
given:
(1) a+%2B+b+=+15
(2) .34a+%2B+.23b+=+4.44
Multiply both sides of (1) by .23 and
subtract from (2)
(2) .34a+%2B+.23b+=+4.44
(1) -.23a+-+.23b+=+-.23%2A15
------------------------------
(2) .34a+%2B+.23b+=+4.44
(1) -.23a+-+.23b+=+-3.45
.11a+=+.99
a+=+9
And, since
(1) a+%2B+b+=+15
b+=+15+-+a
b+=+6
9 of the $.34 stamps were sold and
6 of the $.23 stamps were sold
check:
(2) .34a+%2B+.23b+=+4.44
.34%2A9+%2B+.23%2A6+=+4.44
3.06+%2B+1.38+=+4.44
4.44+=+4.44
OK


Trigonometry-basics/180794: This question is from textbook Analytic Trigonometry
Standing on the bank of a river, a surveyor measures the angle to the top of a tree on the opposite bank to be 23 degrees. He backs up 45ft and remeasures the angle to the top of the tree at 18 degrees. How wide is the river?
1 solutions

Answer 135530 by josmiceli(9817) About Me  on 2009-02-07 19:45:06 (Show Source):
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Let the width of the river = w ft
Let the height of the tree = h ft
given:
(1) tan%2823%29+=+h%2Fw
(2) tan%2818%29+=+h%2F%2845+%2B+w%29
These are 2 equations with 2 unknowns, so
they should be solvable
tan%2823%29+=+.4245
tan%2818%29+=+.3249
(1) .4245+=+h%2Fw
(2) .3249+=+h%2F%2845+%2B+w%29
----------------------------
Multiply both sides of (1) by w
Multiply both sides of (2) by 45+%2B+w
(1) .4245w+=+h
(2) .3249%2A%2845+%2B+w%29+=+h
(2) 14.6214+%2B+.3249w+=+h
Subtract (2) from (1)
(1) .4245w+=+h
(2) -14.6214+-+.3249w+=+-h
.0996w+-+14.6214+=+0
.0996w+=+14.6214
w+=+14.6214%2F.0996
w+=+146.8012
.8012%2A12+=+9.61
The river is 146 ft 9 in wide
check answer:
(2) tan%2818%29+=+h%2F%2845+%2B+w%29
.3249+=+h%2F191.8012
h+=+.3249%2A191.8012
h+=+62.3162 ft the height of the tree
(1) tan%2823%29+=+h%2Fw
.4245+=+62.3162%2F146.8012
.4245+=+.424494 close enough


Square-cubic-other-roots/180689: what is the square root of 125x^2? (square root of 125x squared?

1 solutions

Answer 135424 by josmiceli(9817) About Me  on 2009-02-06 21:06:38 (Show Source):


Quadratic_Equations/180687: I need help please show me an example of a complex roots equation. Thanks
1 solutions

Answer 135421 by josmiceli(9817) About Me  on 2009-02-06 21:02:09 (Show Source):
You can put this solution on YOUR website!
Suppose the roots are i+%2B+1 and i+-+1, then
the equation can be factored into
%28x+-+%281+%2B+i%29%29 and %28x+-+%281+-+i%29%29, so
%28x+-+%281+%2B+i%29%29%28x+-+%281+-+i%29%29+=+0
Note that if you replace x by either 1+%2B+i or 1+-+i,
Then the equation is solved
Now multiplying the factors:
x%5E2+-%281+%2B+i%29x+-+%281+-+i%29x+%2B+%281+%2B+i%29%281+-+i%29+=+0
x%5E2+-+x+-+ix+-+x+%2B+ix+%2B+1+%2B+i+-+i+-+i%5E2+=+0
(note that i%5E2+=+-1 and -i%5E2+=+%2B1)
x%5E2+-+x+-+ix+-+x+%2B+ix+%2B+1+%2B+i+-+i+-+i%5E2+=+x%5E2+-+2x+%2B+2
x%5E2+-+2x+%2B+2+=+0 is the equation to find roots
y+=+x%5E2+-+2x+%2B+2 is the complete complex roots equation
There are 2 complex roots to this equation,
1+%2B+i and 1+-+i
Graphing it, you can see it doesn't intersect the x-axis, where
real roots would be:
+graph%28+500%2C+500%2C+-10%2C+10%2C+-10%2C+10%2C+x%5E2+-+2x+%2B+2%29+



Rate-of-work-word-problems/180686: Jim can fill a pool carrying buckets of water in 30 minutes. Sue can do the same job in 45 minutes. Tony can do the same job in 1 ½ hours. How quickly can all three fill the pool together?
1 solutions

Answer 135417 by josmiceli(9817) About Me  on 2009-02-06 20:40:50 (Show Source):
You can put this solution on YOUR website!
In words:
Let x= number of hours for Jim, Sue, and Tony to
fill pool working together
Jim's rate of filling + Sues rate of filling + Tony's rate of filling =
rate of all 3 filling pool together
1%2F.5+%2B+1%2F.75+%2B+1%2F1.5+=+1%2Fx
Multiply both sides by 1.5x
3x+%2B+2x+%2B+x+=+1.5
6x+=+1.5
x+=+.25 hr
All 3 filling pool together can do the job in 15 min


Reduction-of-unit-multipliers/180684: This question is from textbook algebra1/2 an incremental development
Use two unit multiplyers to convert 10,000 square inches to square feet. Round any decimal answer to two places.
1 solutions

Answer 135415 by josmiceli(9817) About Me  on 2009-02-06 20:32:07 (Show Source):
You can put this solution on YOUR website!
10000 in2 x 1 ft2 / 12%5E2 in2 =
10000 in2 x 1 ft2 / 144 in2 =
69.44 ft2 answer


Linear-systems/180671: This question is from textbook Algebra 1
2m + n = 1
m - n = 8
1 solutions

Answer 135400 by josmiceli(9817) About Me  on 2009-02-06 17:22:37 (Show Source):
You can put this solution on YOUR website!
There are 2 equations and 2 unknowns,
so it is solvable. If there were more
unknowns than equations it would be
unsolvable
(1) 2m+%2B+n+=+1
(2) m+-+n+=+8
Just add the equations
2m+%2B+m+%2B+n+-+n+=+1+%2B+8
3m+=+9
Divide both sides by 3
%283m%29%2F3+=+9%2F3
m+=+3
As long as I do the same thing to both
sides, the equation is still true.
Put m+=+3 back into (2)
3+-+n+=+8
Subtract 3 from both sides
-n+=+8+-+3
-n+=+5
Multiply both sides by -1
n+=+-5
The solution is m+=+3 and n+=+-5


Coordinate-system/180585: A motorboat went 10 miles upstream in 1 hour. The return trip took only 30 minutes. Assume that the "water speed" and the current speed were constant during both parts of the trip. Find the water speed of the boat and the current speed.
1 solutions

Answer 135382 by josmiceli(9817) About Me  on 2009-02-06 12:17:26 (Show Source):
You can put this solution on YOUR website!
Let r%5Bb%5D= the speed of the boat in still water
Let r%5Bc%5D= the speed of the current
For the trip upstream:
(1) d%5Bu%5D+=+r%5Bu%5D%2At%5Bu%5D
For the trip downstream:
(2) d%5Bd%5D+=+r%5Bd%5D%2At%5Bd%5D
given:
d%5Bu%5D+=+10 mi
d%5Bd%5D+=+10 mi
t%5Bu%5D+=+1 hr
t%5Bd%5D+=+.5 hr
upstream:
r%5Bu%5D+=+r%5Bb%5D+-+r%5Bc%5D
r%5Bd%5D+=+r%5Bb%5D+%2B+r%5Bc%5D
------------------------
(1) d%5Bu%5D+=+r%5Bu%5D%2At%5Bu%5D
(1) 10+=+r%5Bu%5D%2A1
(1) 10+=+%28r%5Bb%5D+-+r%5Bc%5D%29%2A1
(1) 10+=+r%5Bb%5D+-+r%5Bc%5D
and
(2) d%5Bd%5D+=+r%5Bd%5D%2At%5Bd%5D
(2) 10+=+r%5Bd%5D%2A.5
(2) 10+=+%28r%5Bb%5D+%2B+r%5Bc%5D%29%2A.5
(2) 10+=+.5r%5Bb%5D+%2B+.5r%5Bc%5D
-------------------------------
Subtract (2) from (1)
(1) 10+=+r%5Bb%5D+-+r%5Bc%5D
(2) -10+=+-.5r%5Bb%5D+-+.5r%5Bc%5D
(3) 0+=+.5r%5Bb%5D+-+1.5r%5Bc%5D
1.5r%5Bc%5D+=+.5r%5Bb%5D
3r%5Bc%5D+=+r%5Bb%5D
Now I can rewrite (1)
(1) 10+=+r%5Bb%5D+-+r%5Bc%5D
(1) 10+=+3r%5Bc%5D+-+r%5Bc%5D
(1) 10+=+2r%5Bc%5D
r%5Bc%5D+=+5 mi/hr
and, since
(1) 10+=+r%5Bb%5D+-+r%5Bc%5D
(1) 10+=+r%5Bb%5D+-+5
(1) r%5Bb%5D+=+15 mi/hr
The speed of ther boat in still water is 15 mi/hr
The speed of the current is 5 mi/hr
check:
(2) 10+=+%28r%5Bb%5D+%2B+r%5Bc%5D%29%2A.5
10+=+%2815+%2B+5%29%2A.5
10+=+20%2A.5
10+=+10
OK



Rational-functions/180611: A circular table is to be made that will have a top covered with material that costs $3.50 per square foot. The covering is to cost no more than $60. What is the maximum radius for the top of the table?
1 solutions

Answer 135379 by josmiceli(9817) About Me  on 2009-02-06 11:53:03 (Show Source):
You can put this solution on YOUR website!
The area of the table is:
pi%2Ar%5E2
In words:
(max cost)/(cost/ft2) = max ft2
60+%2F+3.5+=+120%2F7 ft2
pi%2Ar%5E2+=+120%2F7
r%5E2+=+120%2F%287%2Api%29
r%5E2+=+5.457
r+=+2.336 ft
.336%2A12+=+4
The maximum radius is about 2 ft 4 in


Graphs/180616: please help me solve this problem

Solve the equation 3x - 14 = 1
1 solutions

Answer 135375 by josmiceli(9817) About Me  on 2009-02-06 11:39:43 (Show Source):
You can put this solution on YOUR website!
+3x+-+14+=+1
You MUST do the same thing to BOTH sides of the equation
If you do that, you won't change the truth of the equation,
namely that one side is equal to the other
OK, I'll subtract 1 from both sides
3x+-+14+-+1+=+1+-+1
3x+-+14+-+1+=+0 (note that in this step, I'm just rewriting it,
not doing the same thing to both sides)
3x+-+15+=+0 (again, I'm just rewriting it)
Now I will add 15 to both sides
3x+-+15+%2B+15+=+0+%2B+15
3x+=+15 (just rewriting it)
Now I will divide both sides by 3
%283x%29%2F3+=+15%2F3 (I did the same thing to both sides)
x+=+5 answer
(note that %283x%29%2F3 is the same as %283%2F3%29%2Ax


Trigonometry-basics/180507: Write the trig function as an algebraic expression: sin(2arctanx)
PLEASE HELP ME!!! I really don't know what to do.
1 solutions

Answer 135306 by josmiceli(9817) About Me  on 2009-02-05 21:17:32 (Show Source):
You can put this solution on YOUR website!
You have to say this one in a way that makes sense
In words:
First, "arctan(x)" means "the angle whose tangent is x"
Therefore, "2*arctan(x)" means twice the angle whose tangent is x"
Now I can read the whole thing as:
"the sine of twice the angle whose tangent is x"
If the tangent is x%2F1, then the sine is x%2Fsqrt%28x%5E2+%2B+1%29
and the cosine is 1%2Fsqrt%28x%5E2+%2B+1%29
The double angle formula for sine is:
sin%282a%29+=+2%2Asin%28a%29%2Acos%28a%29
sin%282a%29+=+2%2A%28x%2Fsqrt%28x%5E2+%2B+1%29%29%2A%281%2Fsqrt%28x%5E2+%2B+1%29%29
sin%282a%29+=+%282x%29+%2F+%28x%5E2+%2B+1%29 answer
Suppose the angle was 45 degrees. Then x=1 and
sin%282a%29+=+%282x%29+%2F+%28x%5E2+%2B+1%29
sin%2890%29+=+2+%2F+2
sin%2890%29+=+1 and this is true


percentage/180544: In trying to find what 8% of 5% is, would i need to convert both percentages into a fraction? What is the process I would complete to find the answer
1 solutions

Answer 135302 by josmiceli(9817) About Me  on 2009-02-05 20:55:35 (Show Source):
You can put this solution on YOUR website!
All you have to do is multiply 8% and 5%
.08%2A.05+=+.004, or .4 %
If you do a simpler one, like
50% of 50% of 50%, you get
.5%2A.5%2A.5+=+.125, or 12.5 %


Distributive-associative-commutative-properties/180535: Use FOIL to multiply:
(5x - 6)(3x - 4)
Show Steps!
1 solutions

Answer 135298 by josmiceli(9817) About Me  on 2009-02-05 20:46:09 (Show Source):
You can put this solution on YOUR website!
Practice doing it this way, and you'll catch on:
Suppose I have
13%2A41+=+533
Now I'll separate the number into 2 factors, let's say
%289+%2B+4%29%2825+%2B+16%29
I believe FOIL stands for first-outer-inner-last
Following this, I get
%289+%2B+4%29%2825+%2B+16%29+=+9%2A25+%2B+9%2A16+%2B+4%2A25+%2B+4%2A16
%289+%2B+4%29%2825+%2B+16%29+=+225+%2B+144+%2B+100+%2B+64
%289+%2B+4%29%2825+%2B+16%29+=+533
Try a simpler one, like
5%2A11+=+55
5%2A11+=+%283+%2B+2%29%287+%2B+4%29
%283+%2B+2%29%287+%2B+4%29+=+3%2A7+%2B+3%2A4+%2B+2%2A7+%2B+2%2A4
%283+%2B+2%29%287+%2B+4%29+=+21+%2B+12+%2B+14+%2B+8
%283+%2B+2%29%287+%2B+4%29+=+55
After practice this way, you can put in x's and
y's anywhere you like, and you'll get correct
answers


Expressions-with-variables/180513: 5x-y=-18
4x+2y=92
These are both the same problem.I don't get how to do these problems.Could you explain to me how to do this type of problem please?
1 solutions

Answer 135293 by josmiceli(9817) About Me  on 2009-02-05 20:31:31 (Show Source):
You can put this solution on YOUR website!
What they are is 2 equations with 2
unknowns, so I can assume you are to
solve for x and y
(1) 5x+-+y+=+-18
(2) 4x+%2B+2y+=+92
They should be solvable. If I graph them,
they are 2 intersecting straight lines
and the solution, (x,y) is where they
intersect. I'll graph them
+graph%28+500%2C+500%2C+-50%2C+50%2C+-50%2C+80%2C+5x+%2B+18%2C-2x+%2B+46%29+
Looking at the graph, the intersection is at about x+=+4,
y+=+38, so the solution would be (4,38)
Now I'll find the actual solution
(1) 5x+-+y+=+-18
(2) 4x+%2B+2y+=+92
Multiply both sides of (1) by 2 and add the equations
(1) 10x+-+2y+=+-36
(2) 4x+%2B+2y+=+92
14x+=+56
x+=+4
Now put this value of x back into (1)
(1) 10x+-+2y+=+-36
10%2A4+-+2y+=+-36
40+-+2y+=+-36
2y+=+40+%2B+36
2y+=+76
y+=+38
So, I guessed right. The solution is
(4,38), or in other words,
x+=+4
y+=+38


percentage/180528: Express the following percent in decimal and in fraction form (in lowest terms).
0.02% = I understand that it's decimal form is 0.0002 but I don't understand why it's fraction format would not be 0.02/100 instead of 1/5,000.
1 solutions

Answer 135280 by josmiceli(9817) About Me  on 2009-02-05 20:11:22 (Show Source):
You can put this solution on YOUR website!
It's because a fraction has whole numbers in the
numerator and denominator
.0002+=+2%2A10%5E-4
2%2A10%5E-4+=+2%2F10%5E4
2%2F10%5E4+=+1%2F5000