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Mathtut answered: 3667 problems
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Graphs/172871: how do i know if the value is a solution, i need to provide a value that is not a solution. If the value is not a solution, i need to provide a value that is a solution. how do i do this for -2< x <4?

1 solutions

Answer 127720 by Mathtut(3670) About Me  on 2008-12-11 20:09:23 (Show Source):
You can put this solution on YOUR website!
x, is isolated like you want the simply states
:
that x has the value of anything greater than -2 and less than 4.....that is the solution set.
It would look something like this on the number line. The -2 and 4 should be hollow circles since they are not inclusive and everything in between those numbers are a solution.

number_line%28+600%2C+-10%2C+10%2C+-2%2C4+%29


Functions/172863: The total value of quarters and nickels in a jar = 7.70. If the nickels were quarters and the quarters were nickels, the toal value of coins would be 4.90. Find the number of nickels.
1 solutions

Answer 127718 by Mathtut(3670) About Me  on 2008-12-11 19:54:33 (Show Source):
You can put this solution on YOUR website!
let n be the number of nickels and q be the number of quarters
:
.05n+.25q=7.70
.05q+.25n=4.90---->.25n+.05q=4.90
:
mulitply 1st equation by -5
:
-.25n+-1.25q=-38.5..revised eq 1
.25n+ .05q=4.90
:
-1.2q=-33.6
:
highlight%28q=28%29quarters
:
.05n+.25(28)=7.70
:
.05n=.70
:
highlight%28n=14%29nickels
:


Linear-equations/172855: the scale factor is 2 the coordinates of a,b,c is a:(-8,-3) b: (-3,0) c:(-2,3)
what are the new coordinates now
the scale factor is 3. what are the coordinates a,b,c
1 solutions

Answer 127715 by Mathtut(3670) About Me  on 2008-12-11 19:38:31 (Show Source):
You can put this solution on YOUR website!
divide by 2 the original coordinates would be a(-4,-3/2) b (-3/2,0) c (-1,3/2)
:
a scale factor of 3 would produce (a(-12,-9/2) b (-9/2,0) c (-3,9/2)
simply by multiplying by 3


Inequalities/172695: Hi,
Please help with this inequality word problem.
A farmer has 29,000 pounds of nitrogen available for growing honeydews, yellow onions and lettuce on her farm. One acre of each of these crops requires 120,150, and 180pounds of nitrogen, respectively. If we let h,y,and l designate the number of acres to be planted of honeydews, yellow onions, and lettuce, write an inequality which reflects the limitations imposed by the nitrogen:(Hint: It is not necessary to use it all.)
Thanks,
Freedom45
1 solutions

Answer 127713 by Mathtut(3670) About Me  on 2008-12-11 19:23:02 (Show Source):
You can put this solution on YOUR website!
the hint just means it doesnt have to equal 29000.
so with the labels that they gave.
:
highlight%28120h%2B150y%2B180l%3C=29000%29
what that is saying is 120 pounds per acre of honeydew +150 pounds per acre of onions+ 180 pounds per acre of lettuce cannot exceed 29000 pounds of nitrogen.


Graphs/172739: In 2004, German driver hrfj won the U.S. race. His speed was approx. 113.523 miles per hour write a direct variation equation for the distance D that hrfj drove in H hours at that speed

1 solutions

Answer 127706 by Mathtut(3670) About Me  on 2008-12-11 19:06:05 (Show Source):
You can put this solution on YOUR website!
D=113.523%28H%29 or D%2FH=113.523 meaning D and H are directly related
:
and have a constant value of 113.523


Mixture_Word_Problems/172837: solve
a) -9X-10<-46 PUT A LINE UNDER< SIGN
B) -6<3(x-1)<12 put a line under the first<
1 solutions

Answer 127691 by Mathtut(3670) About Me  on 2008-12-11 18:29:38 (Show Source):
You can put this solution on YOUR website!
a)-9x-10%3C=-46add 10 to both sides of equation
:
-9x%3C=-36 now divide both sides by -9 remembering that dividing by a
:
negative reverses the inequality sign.
:
highlight%28x%3E=4%29
:
b)-6%3C=3%28x-1%29%3C12 distribute the middle term 3(x-1)=3x-3
:
-6%3C=3x-3%3C12now add 3 to all terms
:
-3%3C=3x%3C15now divide all terms by 3 to isolate the x
:
highlight%28-1%3C=x%3C5%29


Proportions/172838: Kim was selected class president. She received 3 votes for every 2 that Amy got. No one else ran. However, if 8 of the people who voted for Kim had voted for Amy instead, Kim would have received only 1 vote for every 2 that Amy would have gotten. How many people voted?
1 solutions

Answer 127688 by Mathtut(3670) About Me  on 2008-12-11 18:20:24 (Show Source):
You can put this solution on YOUR website!
ok the easiest way to set this up is with proportions
:
lets call votes kim receives k and votes amy receives a
:
k%2Fa=3%2F2--->2k=3a---->k=3a/2......eq 1
:
%28k-8%29%2F%28a%2B8%29=1%2F2----->a+8=2(k-8)--->a+8=2k-16--->a-2k=-24....eq 2
:
lets substitute k's value in eq 1 into eq 2
:
a-2(3a/2)=-24
:
a-3a--24
:
-2a=-24
:
highlight%28a=12%29votes for amy
:
highlight%28k=3%2812%29%2F2=18%29votes for kim
Total of people who votedhighlight%2818%2B12=30%29


Equations/172815: Solve for variable: s= 8/1-t, solve for t
This is a study problem for an Accuplacer test that I'm taking tomorrow, It really helps me to understand if I can See each step to solve this problem written out like in a math book. Thank you
1 solutions

Answer 127685 by Mathtut(3670) About Me  on 2008-12-11 18:10:20 (Show Source):
You can put this solution on YOUR website!
s=8%2F%281-t%29....multiply all terms by 1-t
:
%281-t%29s=8cross%281-t%29%2Fcross%281-t%29
:
s-ts=8.....subtract s from both sides
:
-ts=8-s....divide by -s on both sides
:
cross%28-s%29t%2Fcross%28-s%29=-%288-s%29%2Fs
:
highlight%28t=%28s-8%29%2Fs%29


Signed-numbers/172825: Solve by elimination: x+7y=30, 9x+6y=99
It really helps me to understand if I can See each step to solve this problem written out like in a math book. Thank you
1 solutions

Answer 127676 by Mathtut(3670) About Me  on 2008-12-11 17:49:48 (Show Source):
You can put this solution on YOUR website!
solving by elimination is simply adding or subtracting one equation from another
:
with the intention of eliminating one of the variables.
:
so lets line the equations up one under the other to have a better look at each variable.
:
x+7y=30....eq 1
9x+6y=99....eq 2
:
ok as you observe these equations we try to do the least amount of manipulation as possible to reach our goal.....we can either multiply eq 1 by -9 and add the equations together thus eliminating the x terms, or we could multiply eq 1 by - and eq 2 by -7 and add the two equations togethr to eliminate the y terms. I choose the first choice
:so -9(x+7y=30) equals -9x-63y=-270..so that is our revised eq 1. lets line them up again.
:
-9x-63y=-270
9x+ 6y=99
:
so you see how if we add these two equations together that the x terms are eliminated because -9x+9x=0. We are left with -63y+6y=-270+99--->
:
-57y=-171...dividing by -57 gives us
:
highlight%28y=3%29.
:
now we take y's value and plug it back into either original equation to solve for x I choose eq 1
:
x+7(3)=30
:
x+21=30
:
highlight%28x=9%29
:
:


Quadratic_Equations/172827: (3i)-(7i)-(-1-i) My teacher gave me the answer which is 1-(3i) I can not figure out how she did and need to know for a test tomorrow Thank you
1 solutions

Answer 127670 by Mathtut(3670) About Me  on 2008-12-11 17:37:22 (Show Source):
You can put this solution on YOUR website!
3i-7i-%28-1-i%29 .......-(-1-i) = 1+i
:
so-4i%2B1%2Bi
:
-3i%2B1or highlight%281-3i%29


Travel_Word_Problems/172806: A frog is at the bottom of 200 foot well. Each day it crawls up 5 feet and each it slips back 2 feet. The day begins at sunrise and ends when night begins at sundown. On which day will the frog first reach the top of the well?
1 solutions

Answer 127657 by Mathtut(3670) About Me  on 2008-12-11 16:54:06 (Show Source):
You can put this solution on YOUR website!
5-2=3feet gain per day...200/3=66.66 this number gives us a reasonable place to start....remember it jumps 5 feet before it loses 2.
:
lets start at day 64 just to give our selves room 64 times 3=192 which is 8 feet from reaching our goal. day 65 starts like this 92+5=97(oh, so close)but then we lose 2 at the end of the day...97-2=95...Damn......
at the end of 65 days the frog will have climbed up 195 feet. On day 66 will the frog finally reach its goal?... the frog leaps and what to his wonder 195+5=200. He made it......damn that must have been tiring....turdles pace..lol


Travel_Word_Problems/172804: It takes 40 minutes to cut a log into 5 pieces. How long would it take to cut a similar log into ten pieces?
1 solutions

Answer 127653 by Mathtut(3670) About Me  on 2008-12-11 16:41:56 (Show Source):
You can put this solution on YOUR website!
this is a direct proportion problem
:
5/40=10/x.....cross multiply and solve for x
:
5x=400
:
highlight%28x=80%29minutes


Equations/172800: This question is from textbook
I am having a bit of trouble on this equation.
here it is if you can please help me: -2k/7=36
my teacher hasnt tought this to us yet
1 solutions

Answer 127651 by Mathtut(3670) About Me  on 2008-12-11 16:33:13 (Show Source):
You can put this solution on YOUR website!
-2k%2F7=36 multiply both sides by 7
:
cross%287%29%28-2k%29%2Fcross%287%29=36%287%29
:
-2k=252 your left with
:
cross%28-2%29k%2Fcross%28-2%29=252%2F-2 dividing both sides by -2
:
highlight%28k=-126%29 252 divided by -2=126


Mixture_Word_Problems/172783: art can do a job in 30 minutes bob can do it in 40 min. and carl can do it in 60 min , how long will it take them all to do the job if they help eachother, write the equation
1 solutions

Answer 127625 by Mathtut(3670) About Me  on 2008-12-11 15:24:14 (Show Source):
You can put this solution on YOUR website!
art can do 1/30 job per minute
:
bob.......1/40 job per minute
:
carl.......1/60 job per minute
those are all rates.....lets call time=t
:
t/30+t/40+t/60=1(job)
:
4t+3t+2t=120...muliply each term by 120
:
9t=120
:
highlight%28t=120%2F9=40%2F3%29or 13 and 1/3 minutes to do the entire job...


Finance/172745: At year end, Ted's Company balance sheet showed total assets of $60 million, total liabilities (including preferred stock) of $45 million, and 1,000,000 shares of common stock outstanding. Next year, Ted is projecting that it will have net income of $1.5 million. If the average PE multiple in Ted’s industry is 15, what should be the price of Ted’s stock?
1 solutions

Answer 127614 by Mathtut(3670) About Me  on 2008-12-11 14:24:09 (Show Source):
You can put this solution on YOUR website!
you must first figure the earnings per share which would be
:
earnings(1.5million)/number of shares(1 million
:
eps=$1.5 (earnings per share)
:
a PE(price per earnings) ratio is simply what your pay in multiples above what the earnings are.....if the earnings are 1.5 dollars per share a 15 PE or multiple would be 15 times that amount
:
therefore $highlight%281.5%2815%29=22.50%29 is the price that would be paid on Ted's stock if the equaled the industry PE multiple of 15.


Numbers_Word_Problems/172776: Twice the sum of two consecutive even integers is 260. Find the integers
1 solutions

Answer 127612 by Mathtut(3670) About Me  on 2008-12-11 14:01:12 (Show Source):
You can put this solution on YOUR website!
lets call our intergers a and a+2
:
2(a+a+2)=260
:
2(2a+2)=260
:
4a+4=260
:
4a=256
:
highlight%28a=64%29integer 1
:
highlight%28a%2B2=64%2B2=66%29integer 2
:


Polynomials-and-rational-expressions/172742: factor completely. 9x^2-36y^2. factor complely. x^2-15wy+3xy-5wx. thank you.
1 solutions

Answer 127588 by Mathtut(3670) About Me  on 2008-12-11 12:16:18 (Show Source):
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%283x%29%5E2-%286y%29%5E2 since 3%5E2=9and 6%5E2=36we are left with the difference of squares here
:
highlight%28%283x%2B6y%29%283x-6y%29%29factoring
:
x%5E2-15wy%2B3xy-5wxlets line up the terms that have like variables
:
-15wy -5wy)so factor out a -5 and w -5w(3y+x)
:
x%5E2%2B3xyso factor out an x.........x(x+3y)
:
do you see any terms that are alike.... that we can factor out of these terms......yes (3y+x)
:
so x%28x%2B3y%29-5w%28x%2B3y%29
factors to
:
highlight%28%28x%2B3y%29%28x-5w%29%29


Polynomials-and-rational-expressions/172712: If you could please help point me in the right direction!!! I need to solve this rational expression:
2 + (4/x-5) = (15/x-4)
I have tried a couple of times, but seem to be off track. I know to find the "LCD" the multiply each side by that... i chose (x-5).
So then i have: [2(x-5)]/1 + [4(x-5)]/(x-5) = [15(x-5)]/(x-4)
I think that is what Im supposed to do, but then I get lost!! Is this the wrong way to apply the "lcd"?
Thank you SO much for your time, Im working on attempt #5... :)

1 solutions

Answer 127560 by Mathtut(3670) About Me  on 2008-12-10 23:56:03 (Show Source):
You can put this solution on YOUR website!
you need to multiply each term by (x-5)(x-4)
:
you should get 2%28x-4%29%28x-5%29%2B4%28x-4%29=15%28x-5%29 distribute this
:
and end up with2x%5E2-29x%2B99=0

Solved by pluggable solver: SOLVE quadratic equation (work shown, graph etc)
Quadratic equation ax%5E2%2Bbx%2Bc=0 (in our case 2x%5E2%2B-29x%2B99+=+0) has the following solutons:

x%5B12%5D+=+%28b%2B-sqrt%28+b%5E2-4ac+%29%29%2F2%5Ca

For these solutions to exist, the discriminant b%5E2-4ac should not be a negative number.

First, we need to compute the discriminant b%5E2-4ac: b%5E2-4ac=%28-29%29%5E2-4%2A2%2A99=49.

Discriminant d=49 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28--29%2B-sqrt%28+49+%29%29%2F2%5Ca.

x%5B1%5D+=+%28-%28-29%29%2Bsqrt%28+49+%29%29%2F2%5C2+=+9
x%5B2%5D+=+%28-%28-29%29-sqrt%28+49+%29%29%2F2%5C2+=+5.5

Quadratic expression 2x%5E2%2B-29x%2B99 can be factored:
2x%5E2%2B-29x%2B99+=+%28x-9%29%2A%28x-5.5%29
Again, the answer is: 9, 5.5. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+2%2Ax%5E2%2B-29%2Ax%2B99+%29


Quadratic_Equations/172677: Solve x.
x^2+2^x = 100
1 solutions

Answer 127559 by Mathtut(3670) About Me  on 2008-12-10 23:49:29 (Show Source):
You can put this solution on YOUR website!
x%5E2%2B2x-100=0
:
Solved by pluggable solver: SOLVE quadratic equation (work shown, graph etc)
Quadratic equation ax%5E2%2Bbx%2Bc=0 (in our case 1x%5E2%2B2x%2B-100+=+0) has the following solutons:

x%5B12%5D+=+%28b%2B-sqrt%28+b%5E2-4ac+%29%29%2F2%5Ca

For these solutions to exist, the discriminant b%5E2-4ac should not be a negative number.

First, we need to compute the discriminant b%5E2-4ac: b%5E2-4ac=%282%29%5E2-4%2A1%2A-100=404.

Discriminant d=404 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28-2%2B-sqrt%28+404+%29%29%2F2%5Ca.

x%5B1%5D+=+%28-%282%29%2Bsqrt%28+404+%29%29%2F2%5C1+=+9.04987562112089
x%5B2%5D+=+%28-%282%29-sqrt%28+404+%29%29%2F2%5C1+=+-11.0498756211209

Quadratic expression 1x%5E2%2B2x%2B-100 can be factored:
1x%5E2%2B2x%2B-100+=+%28x-9.04987562112089%29%2A%28x--11.0498756211209%29
Again, the answer is: 9.04987562112089, -11.0498756211209. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+1%2Ax%5E2%2B2%2Ax%2B-100+%29


Complex_Numbers/172686: i really need help with this. i thought to have an equation in vertex form and to find the vertex you had to have a y variable but in this equation there is no y. Please help me it will be much appreciated.

Write the quadratic function in vertex form. Then, identify the vertex.
x^2-8x+11=0
1 solutions

Answer 127558 by Mathtut(3670) About Me  on 2008-12-10 23:43:56 (Show Source):
You can put this solution on YOUR website!
x%5E2-8x%2B16-16%2B11=0completing the square
%28x-4%29%5E2-5=0factoring
y=%28x-4%29%5E2-5 vertex is at(4,-5)


Quadratic_Equations/172689: This question is from textbook
I really dont understand this problem can some pleas help me thank you
A business invests $10,000 in a savings account for two years. At the beginning of the second year, an additional $3500 is invested. At the end of the second year, the account balance is $15,569.75. What was the annual interest rate?

1 solutions

Answer 127557 by Mathtut(3670) About Me  on 2008-12-10 23:35:21 (Show Source):
You can put this solution on YOUR website!
2.10000(x+1)(x+1)+3500(x+1)=15569.75------>where x is the interest rate
.... dealing with a quadratic formula.....
when you solve this email me and I will let you know if you have the correct answer.
10000%28x%5E2%2B2x%2B1%29%2B3500x%2B3500=15569.75
:
10000x%5E2%2B20000x%2B10000%2B3500x%2B3500=15569.75
:
10000x%5E2%2B23500x-2069.75=0
:
drop the negative valuesystem%28x=.085%2Cx=-2.64%29
:
highlight%28x=.085%29or 8.5%
Solved by pluggable solver: SOLVE quadratic equation with variable
Quadratic equation ax%5E2%2Bbx%2Bc=0 (in our case 10000x%5E2%2B23500x%2B-2069+=+0) has the following solutons:

x%5B12%5D+=+%28b%2B-sqrt%28+b%5E2-4ac+%29%29%2F2%5Ca

For these solutions to exist, the discriminant b%5E2-4ac should not be a negative number.

First, we need to compute the discriminant b%5E2-4ac: b%5E2-4ac=%2823500%29%5E2-4%2A10000%2A-2069=635010000.

Discriminant d=635010000 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28-23500%2B-sqrt%28+635010000+%29%29%2F2%5Ca.

x%5B1%5D+=+%28-%2823500%29%2Bsqrt%28+635010000+%29%29%2F2%5C10000+=+0.0849702377437334
x%5B2%5D+=+%28-%2823500%29-sqrt%28+635010000+%29%29%2F2%5C10000+=+-2.43497023774373

Quadratic expression 10000x%5E2%2B23500x%2B-2069 can be factored:
10000x%5E2%2B23500x%2B-2069+=+10000%28x-0.0849702377437334%29%2A%28x--2.43497023774373%29
Again, the answer is: 0.0849702377437334, -2.43497023774373. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+10000%2Ax%5E2%2B23500%2Ax%2B-2069+%29




Inequalities/172692: Hi All,
I need help with this inequality word problem.
A furniture manufacturer makes and sells chairs and sofas. He makes a profit of $60 on each chair and $80 on each sofa. If x=number of chairs, and y=number of sofas, write and inequality that says that he would like to make a total profit of a least $4000 this month:
Thank you for your help.
Freedom45
1 solutions

Answer 127556 by Mathtut(3670) About Me  on 2008-12-10 23:33:27 (Show Source):
You can put this solution on YOUR website!
let us call P profit and P=4000
:
highlight%2860x%2B80y%3E=4000%29


Graphs/172711: find the x-intecept of the line 5x-y=-5

1 solutions

Answer 127555 by Mathtut(3670) About Me  on 2008-12-10 23:29:35 (Show Source):
You can put this solution on YOUR website!
x intercept is found when y is set to zero
:
5x-0=-5
:
5x=-5
:
highlight%28x=-1%29 x intercept (-1,0)


Rate-of-work-word-problems/172655: wORKLOAD =10000 APPRAISALS
7000 rESIDENTAIL
2500 cOMMERCIAL
500 iNDUDTRIAL
5 RESIDENTIAL OR COMMERCIAL PROPERTIES CAN BE DONE IN ONE DAY AND 2 INDUSTRIAL PROPERTIES CAN BE DONE IN ONE DAY. hOW MANY APPRAISERS ARE REQUIRED IF WE ASSUME A 240/DAY WORKYEAR?
1 solutions

Answer 127513 by Mathtut(3670) About Me  on 2008-12-10 19:59:28 (Show Source):
You can put this solution on YOUR website!
lets call residents,commercial and industrial r,c,and i
:
5r/day
5c/day
2i/day
:
7000/5=1400 work days
2500/5=500 work days
500/2=250 work days
:
total work days to appraise the 10000 appraisals is 2150 work days
if each person works 240 days a year then the number needed would be
:
2150/240=8.95 rounding up
:
9 appraisers are needed assuming of course each appraiser can do any of the 3 types of appraisals....


Distributive-associative-commutative-properties/172653: Which one of the properties is mostly commonly used in Algebra and why?
1 solutions

Answer 127512 by Mathtut(3670) About Me  on 2008-12-10 19:51:38 (Show Source):
You can put this solution on YOUR website!
in my opinion it is the distributive property. You see it in almost every problem.


Sequences-and-series/172636: write a formula for the general (nth term) of the following arithmetic sequence. then use the formula to find the 101st term
5, 8, 11, 14, 17, 20 ...
1 solutions

Answer 127509 by Mathtut(3670) About Me  on 2008-12-10 19:38:19 (Show Source):
You can put this solution on YOUR website!
2+3n...where n is the natural numbers
:
101st term
:
2+3(101)=305


Money_Word_Problems/172637: This question is from textbook
please help me out with this problem
A business invests $10,000 in a savings account for two years. At the beginning of the second year, an additional $3500 is invested. At the end of the second year, the account balance is $15,569.75. What was the annual interest rate?
1 solutions

Answer 127500 by Mathtut(3670) About Me  on 2008-12-10 18:59:43 (Show Source):
You can put this solution on YOUR website!
2.10000(x+1)(x+1)+3500(x+1)=15569.75------>where x is the interest rate
.... dealing with a quadratic formula.....
when you solve this email me and I will let you know if you have the correct answer.
10000%28x%5E2%2B2x%2B1%29%2B3500x%2B3500=15569.75
:
10000x%5E2%2B20000x%2B10000%2B3500x%2B3500=15569.75
:
10000x%5E2%2B23500x-2069.75=0
:
drop the negative valuesystem%28x=.085%2Cx=-2.64%29
:
highlight%28x=.085%29or 8.5%
Solved by pluggable solver: SOLVE quadratic equation with variable
Quadratic equation ax%5E2%2Bbx%2Bc=0 (in our case 10000x%5E2%2B23500x%2B-2069+=+0) has the following solutons:

x%5B12%5D+=+%28b%2B-sqrt%28+b%5E2-4ac+%29%29%2F2%5Ca

For these solutions to exist, the discriminant b%5E2-4ac should not be a negative number.

First, we need to compute the discriminant b%5E2-4ac: b%5E2-4ac=%2823500%29%5E2-4%2A10000%2A-2069=635010000.

Discriminant d=635010000 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28-23500%2B-sqrt%28+635010000+%29%29%2F2%5Ca.

x%5B1%5D+=+%28-%2823500%29%2Bsqrt%28+635010000+%29%29%2F2%5C10000+=+0.0849702377437334
x%5B2%5D+=+%28-%2823500%29-sqrt%28+635010000+%29%29%2F2%5C10000+=+-2.43497023774373

Quadratic expression 10000x%5E2%2B23500x%2B-2069 can be factored:
10000x%5E2%2B23500x%2B-2069+=+10000%28x-0.0849702377437334%29%2A%28x--2.43497023774373%29
Again, the answer is: 0.0849702377437334, -2.43497023774373. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+10000%2Ax%5E2%2B23500%2Ax%2B-2069+%29




Money_Word_Problems/172638: This question is from textbook
Ineed your help once again I try own my own and my answer are looking craazt help is needed. Thank you so much
Steve traveled 200 miles at a certain speed. Had he gone 10mph faster, the trip would have taken 1 hour less. Find the speed of his vehicle
can you show me this one too.
The Hudson River flows at a rate of 3 miles per hour. A patrol boat travels 60 miles upriver, and returns in a total time of 9 hours. What is the speed of the boat in still water?

1 solutions

Answer 127498 by Mathtut(3670) About Me  on 2008-12-10 18:55:34 (Show Source):
You can put this solution on YOUR website!
I set up the equations you solve
:
d=rt........in both instances distance is equal
lets call the rate of the slow trip r and time t
lets call the rate of the fast trip r+10 and time(t-1)
:
so 200=rt...eq 1
...200=(r+10)(t-1)..eq 2
:change eq 1 to t=200/r and substitute it into eq 2 and solve for r...this will involves a quadratic equation again
:
200=%28r%2B10%29%28%28200%2Fr%29-1%29
:
200=%28r%2B10%29%28%28200-r%29%2Fr%29
:
200r=%28r%2B10%29%28200-r%29
:
200r=200r-r%5E2%2B2000-10r
:
r%5E2%2B10r-2000=0
throw out negative valuesystem%28r=40%2Cr=-50%29
so highlight%28r=40%29mph and highlight%28r%2B10%29=50mph
:
Solved by pluggable solver: SOLVE quadratic equation with variable
Quadratic equation ar%5E2%2Bbr%2Bc=0 (in our case 1r%5E2%2B10r%2B-2000+=+0) has the following solutons:

r%5B12%5D+=+%28b%2B-sqrt%28+b%5E2-4ac+%29%29%2F2%5Ca

For these solutions to exist, the discriminant b%5E2-4ac should not be a negative number.

First, we need to compute the discriminant b%5E2-4ac: b%5E2-4ac=%2810%29%5E2-4%2A1%2A-2000=8100.

Discriminant d=8100 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28-10%2B-sqrt%28+8100+%29%29%2F2%5Ca.

r%5B1%5D+=+%28-%2810%29%2Bsqrt%28+8100+%29%29%2F2%5C1+=+40
r%5B2%5D+=+%28-%2810%29-sqrt%28+8100+%29%29%2F2%5C1+=+-50

Quadratic expression 1r%5E2%2B10r%2B-2000 can be factored:
1r%5E2%2B10r%2B-2000+=+1%28r-40%29%2A%28r--50%29
Again, the answer is: 40, -50. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+1%2Ax%5E2%2B10%2Ax%2B-2000+%29


:
:
:
:
Let s= speed of the boat in still water
The current =3 mi/hr
we know that d=rt or d/r=t for this problem we must break this up into 2 parts
(distance upriver)/(rate going upriver)
+ (distance downriver)/(rate going downriver) = 9 hrs
:the we know the distance is 60 each way
the rate going up stream is 60/s-3
the rate going down stream is 60/s+3
:
so we have 60%2F%28s-3%29%2B60%2F%28s%2B3%29=9again a quadratic equation
:
:
multiply each term by (s+3)(s-3)
:
60%28s%2B3%29%2B60%28s-3%29=9%28s%2B3%29%28s-3%29
60s%2B180%2B60s-180=9%28s%5E2-9%29
120s=9s%5E2-81
9s%5E2-120s-81=0
:
drop the negative valuesystem%28s=13.98%2Cs=-.64%29
:
so highlight%28s=14%29 mph

Solved by pluggable solver: SOLVE quadratic equation with variable
Quadratic equation as%5E2%2Bbs%2Bc=0 (in our case 9s%5E2%2B-120s%2B-81+=+0) has the following solutons:

s%5B12%5D+=+%28b%2B-sqrt%28+b%5E2-4ac+%29%29%2F2%5Ca

For these solutions to exist, the discriminant b%5E2-4ac should not be a negative number.

First, we need to compute the discriminant b%5E2-4ac: b%5E2-4ac=%28-120%29%5E2-4%2A9%2A-81=17316.

Discriminant d=17316 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28--120%2B-sqrt%28+17316+%29%29%2F2%5Ca.

s%5B1%5D+=+%28-%28-120%29%2Bsqrt%28+17316+%29%29%2F2%5C9+=+13.9772373998204
s%5B2%5D+=+%28-%28-120%29-sqrt%28+17316+%29%29%2F2%5C9+=+-0.643904066487102

Quadratic expression 9s%5E2%2B-120s%2B-81 can be factored:
9s%5E2%2B-120s%2B-81+=+9%28s-13.9772373998204%29%2A%28s--0.643904066487102%29
Again, the answer is: 13.9772373998204, -0.643904066487102. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+9%2Ax%5E2%2B-120%2Ax%2B-81+%29





Numbers_Word_Problems/172633: This question is from textbook Algebra Structure and Method Book 1
The numerator equals the sum of the two digits in the denominator. The value of the fraction is 1/4. When both numerator and demonimator are increased by 3, the resulting fraction as the value 1/3. Find the original fraction.
1 solutions

Answer 127497 by Mathtut(3670) About Me  on 2008-12-10 18:50:29 (Show Source):
You can put this solution on YOUR website!
lets call the numerator a and the denominator b
:
a/b=1/4--->4a=b....eq 1
:
(a+3)/(b+3)=1/3--->3a+9=b+3--->3a=b-6...eq 2
:
take b's value from eq 1 and plug it into eq 2
:
3a=4a-6
:
highlight%28a=6%29
highlight%28b=4%286%29=24%29
6/24=1/4
(6+3)/(24+3)=9/27=1/3


Miscellaneous_Word_Problems/172628: This question is from textbook Thinking Mathematically
A service that repairs televisions sells maintenance agreements for $11 a year. The average cost for repairing a television is $34 and 5 in every 100 people who purchase maintenance agreements have televisions that require repair. Find the service's expected profit per maintenance agreement.
Where to begin.... can't really figure this one out anyone to help please!
1 solutions

Answer 127495 by Mathtut(3670) About Me  on 2008-12-10 18:37:33 (Show Source):
You can put this solution on YOUR website!
let x be the number of maintenance agreements and P=profit
:
P=11(x))-34(1/20)(x)
:
P=11x-17/10(x)
:
P=97/10(x) so for 100 contracts
:
P=97(100)/10=$970 bucks


Expressions-with-variables/172615: S=n/2(A=t) Solve for A
Thank you for any help.
1 solutions

Answer 127491 by Mathtut(3670) About Me  on 2008-12-10 18:28:24 (Show Source):
You can put this solution on YOUR website!
lets assume that A=t you have is A-t
:
S=(n/2)(A-t)...multiply both sides by 2
:
2S=n(A-t)...divide by n on both sides
:
2S/n=A-t....now add t to both sides
:
highlight%28%282s%2Fn%29%2Bt=A%29