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Quadratic_Equations/366841: f(x)=1/4x^2 find the vertex and line of symmetry
1 solutions

Answer 261507 by Alan3354(30983) About Me  on 2010-11-06 12:30:28 (Show Source):
You can put this solution on YOUR website!
The vertex is the origin.
The line of symmetry is the y-axis.


Equations/366830: can you please help me to solve this equation?
400r=x^2-40x+400
i want the answer in r

1 solutions

Answer 261506 by Alan3354(30983) About Me  on 2010-11-06 12:29:28 (Show Source):
You can put this solution on YOUR website!
400r=x^2-40x+400
r = (x^2-40x+400)/400
-----------------
Like that?
-----------
x^2-40x+400(1-r) = 0
x = 20 ± 20*sqrt(r) or like that?


Geometry_Word_Problems/366843: Hi
I sent this in yesterday and I haven't got a solution as yet. This is a parallelogram problem asking to solve the perimeter. Its a square box on a slant(a Parallelogram. Inside the parallelogram is a angle or triangle to the left side of the parallelogram. Half way up the triangle to the side of the triangle is a measurement of 5cm. The base of the parallelogram has two measurements. 2 cm to the left side with arrows pointing to the end of the parallelogram and the other half of the base being 4cm to the other side of the parallelogram.So the two bases are 2 cm and 4 cm and the middle number is 5 cm. Do you do the problem like this.
A=1/2bh
1/2. 2cm.5cm=10cm and than divide that by 1/2= 5
1/2.4cm.5cm-20cm and than divide that by 1/2= 10
than add 5 and 10 to equal 15 for the perimeter??????
Hope you can understand what I'm saying. Help!!!!
1 solutions

Answer 261505 by Alan3354(30983) About Me  on 2010-11-06 12:24:48 (Show Source):
You can put this solution on YOUR website!
Send a sketch via the thank you note.


Angles/366834: y is parallel to a
1 solutions

Answer 261504 by Alan3354(30983) About Me  on 2010-11-06 12:23:37 (Show Source):


Numbers_Word_Problems/366818: Write two numbers which are odd and have a total greater than 90
1 solutions

Answer 261492 by Alan3354(30983) About Me  on 2010-11-06 10:28:21 (Show Source):
You can put this solution on YOUR website!
45 & 47
There are others.
725 & 3587 for example


Miscellaneous_Word_Problems/366641: Rewrite with positive exponents. Assume that even roots are of nonnegative quantities and that all denominators are nonzero.(2x^(-1/2))^-3
1 solutions

Answer 261491 by Alan3354(30983) About Me  on 2010-11-06 10:27:08 (Show Source):
You can put this solution on YOUR website!
(2x^(-1/2))^-3
= (2^(-3))*(x^3/2))
= x^(3/2)/8


Polynomials-and-rational-expressions/366809: whAT IS THE lcm OF 3X-15,X2-10X+25
1 solutions

Answer 261488 by Alan3354(30983) About Me  on 2010-11-06 10:22:00 (Show Source):
You can put this solution on YOUR website!
Factor both polynomials.


Quadratic_Equations/366798: The height (t) in feet above the ground, of a ball thrown into the air from the top of a building is given by the function of h(t)= -16(t-2)^2+264, where t is the number of seconds the ball has been in the air.
a. From what height was the ball thrown?
b. what height does the ball reach?
c. when does the ball strike the ground?
e. for what values of t does the function have meaning?

1 solutions

Answer 261482 by Alan3354(30983) About Me  on 2010-11-06 09:52:04 (Show Source):
You can put this solution on YOUR website!
The height (t) in feet above the ground, of a ball thrown into the air from the top of a building is given by the function of h(t)= -16(t-2)^2+264, where t is the number of seconds the ball has been in the air.
a. From what height was the ball thrown?
b. what height does the ball reach?
c. when does the ball strike the ground?
e. for what values of t does the function have meaning?
------------
I think h is the height, not t.
h(t)= -16(t-2)^2+264
h(t) = -16t^2 + 64t + 200
---------------------
a. From what height was the ball thrown?
200 feet
b. what height does the ball reach?
264 feet
c. when does the ball strike the ground?
When h = 0
-16t^2 + 64t + 200 = 0
t = 6.062 seconds
e. for what values of t does the function have meaning?
From launch to impact, t = 0 to t = 6.062 seconds
Later than impact, the ball is stationary, h = 0. The meaning is a matter of opinion.


Exponents/366808: a³/4bˉ² How do you do this problem?
1 solutions

Answer 261480 by Alan3354(30983) About Me  on 2010-11-06 09:43:24 (Show Source):
You can put this solution on YOUR website!
Depends on what you want to do.


test/366727: ^2¥=2 is
1 solutions

Answer 261476 by Alan3354(30983) About Me  on 2010-11-06 09:17:44 (Show Source):


Probability-and-statistics/366801: 5. Show all work. A disc jockey has 10 songs to play. Seven are slow songs, and three are fast songs. Each song is to be played only once. In how many ways can the disc jockey play the 10 songs if
* The songs can be played in any order.
* The first song must be a slow song and the last song must be a slow song.
* The first two songs must be fast songs
1 solutions

Answer 261475 by Alan3354(30983) About Me  on 2010-11-06 09:15:04 (Show Source):
You can put this solution on YOUR website!
A disc jockey has 10 songs to play. Seven are slow songs, and three are fast songs. Each song is to be played only once. In how many ways can the disc jockey play the 10 songs if
* The songs can be played in any order.
The 1st is 1 of 10, then 1 of 9, 8, 7 etc
= 10*9*8*7... = 10!
-------------------
* The first song must be a slow song and the last song must be a slow song.
The 1st is 1/7, the last is 1/6. The other 8 are 1 of 8, 7, 6, 5, 4, 3, 2, 1
= 7*6*(8!)
-------------
* The first two songs must be fast songs
3*2*(8!)


absolute-value/366795: if |x - 12 | ≤ and |y - 8 | ≤ 5 what is the greatest possible value of x - y?


1 solutions

Answer 261474 by Alan3354(30983) About Me  on 2010-11-06 09:08:03 (Show Source):
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if |x - 12 | ≤ and |y - 8 | ≤ 5 what is the greatest possible value of x - y?
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|x-12| <= what?


Angles/366777: I have a question. The question is:


"Sketch a pair of hexagons with corresponding angles congruent
but so that the hexagons are not similar"


Is this even possible? I thought if all the angles were congruent, then the polygons were similar. So I don't think it is possible. Thanks.
1 solutions

Answer 261472 by Alan3354(30983) About Me  on 2010-11-06 09:03:29 (Show Source):
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I don't think it's possible either.


Quadratic_Equations/366738: I am doing quadratic equations, the problem is +X%5E2-x-12+ I understand most of it except for when I get to where the problem says x = -1 sqrt(47)/2 I don't know what to do with the square root symbol. I know how to find the vertex but I don't have the roots to graph the parabola, If some one could help me with this I would be grateful.
1 solutions

Answer 261384 by Alan3354(30983) About Me  on 2010-11-05 23:07:31 (Show Source):
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You didn't show an equation. All equations have an equal sign.
If you mean x%5E2+-+x+-+12+=+0 you missed a sign somewhere, it's sqrt(49).
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Solved by pluggable solver: SOLVE quadratic equation (work shown, graph etc)
Quadratic equation ax%5E2%2Bbx%2Bc=0 (in our case 1x%5E2%2B-1x%2B-12+=+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=%28-1%29%5E2-4%2A1%2A-12=49.

Discriminant d=49 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28--1%2B-sqrt%28+49+%29%29%2F2%5Ca.

x%5B1%5D+=+%28-%28-1%29%2Bsqrt%28+49+%29%29%2F2%5C1+=+4
x%5B2%5D+=+%28-%28-1%29-sqrt%28+49+%29%29%2F2%5C1+=+-3

Quadratic expression 1x%5E2%2B-1x%2B-12 can be factored:
1x%5E2%2B-1x%2B-12+=+%28x-4%29%2A%28x--3%29
Again, the answer is: 4, -3. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+1%2Ax%5E2%2B-1%2Ax%2B-12+%29



Polynomials-and-rational-expressions/366683: I've been stuck on this problem for about an hour now and can't seem to figure out the right answer. I appreciate any help I can get. Here is the problem: Joe has a collection of nickels and dimes that is worth $6.20. If the number of dimes was doubled and nickels were decreased by 37, the value of the coins would be worth $4.20. How many nickels and dimes does Joe have?
Thank you for your time.
1 solutions

Answer 261331 by Alan3354(30983) About Me  on 2010-11-05 21:04:11 (Show Source):
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Joe has a collection of nickels and dimes that is worth $6.20. If the number of dimes was doubled and nickels were decreased by 37, the value of the coins would be worth $4.20. How many nickels and dimes does Joe have?
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n = # of nickels
d = # of dimes
5n + 10d = 620
------
5(n-37) + 20d = 420
5n-185 + 20d = 420
5n + 20d = 605
5n + 10d = 620
--------------- Subtract
20d = -15
No meaningful solution.


Trigonometry-basics/366619: Express tan(-315°) as a trigonometric function of an angle in Quadrant 1.
1 solutions

Answer 261329 by Alan3354(30983) About Me  on 2010-11-05 20:57:34 (Show Source):


Trigonometry-basics/366623: Verify that sec(x)-cos(x)=tan(x)sin(x) is an identity.
1 solutions

Answer 261287 by Alan3354(30983) About Me  on 2010-11-05 17:40:09 (Show Source):
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sec(x)-cos(x)=tan(x)sin(x)
Change to sines and cosines
1/cos - cos = (sin/cos)*sin
Multiply by cos
1 - cos^2 = sin^2
I'm convinced.


Polynomials-and-rational-expressions/366568: 3x^2 + 5x + 1 factoring??????
1 solutions

Answer 261232 by Alan3354(30983) About Me  on 2010-11-05 13:44:04 (Show Source):
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Not factorable.


Quadratic_Equations/366556: Evening All,
Right its been a while since i have attempted maths, and have just gone back to further ed. I have attempted the following questions, which im sure should be simple, but of course like anything its just getting back into things after a number of years. i have listed the questions below, and my answers if anybody will take the time to have a quick look and correct me where neccessary i would appreciate this.
1)Find dy/dx by differentiating with respect to x the following expressions.
a) y=x^3-6x^2+9x-1 = 3x^2-12x+8
b) y=1/2x -sqrtx = 1/2-1/2x^-1/2
c) y=e^x-e^-x = e^x+e^-x
d) y=25cosx--sinx = -25sinx-cosx
e) y= 3sinhx-4coshx = 3hsinhx+4hsinhx
f) y= (x^2+1) sinhx = 1
2 Use product rule to obtain dy/dx for the following
a) y=x^2e^x = 2x(e^x)+x^2(e^x)
b) y= xtanx = 1(tanx)+x(sec^2x)
c) y= x^4ln(x)= 4x^3(ln(x))+x^4(1/x)
d) y= x^2sinx = 2x(sinx)+x^2(cosx)
e) y= e^-xcosx = -e^-x(cos x)+ e^-x (-sinx)
f) y=(x^2+1)sinhx = (2x +1) (sinhx)+(x^2+1)(cosh x)
Finally, use the quotient rule to differentiate with respect to x, simplifying as far as possible.
a) y= sinx/1+e^-x = 1+e^-x(cosx)-(1-e^x)sinx/(1+e^-x)^2
b) y= lnx/1+x^2 = 1+x^2(1/x)-1+2x(ln x)/(1+x^2)^2
Really this would be appreciated thank you
1 solutions

Answer 261230 by Alan3354(30983) About Me  on 2010-11-05 13:24:06 (Show Source):
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1)Find dy/dx by differentiating with respect to x the following expressions.
a) y=x^3-6x^2+9x-1 = 3x^2-12x+8 *** + 9
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b) y=1/2x -sqrtx = 1/2-1/2x^-1/2 = (x - sqrt(x))/2x (same answer)
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c) y=e^x-e^-x = e^x+e^-x
d) y=25cosx--sinx = -25sinx-cosx ** there are 2 minus signs??
------------
e) y= 3sinhx-4coshx = 3hsinhx+4hsinhx Is it sin(hx), or hyperbolic?
--------------
f) y= (x^2+1) sinhx = 1
2 Use product rule to obtain dy/dx for the following
a) y=x^2e^x = 2x(e^x)+x^2(e^x)
b) y= xtanx = 1(tanx)+x(sec^2x)
c) y= x^4ln(x)= 4x^3(ln(x))+x^4(1/x) = 4x^3*ln(x) + x^3
-----------------
d) y= x^2sinx = 2x(sinx)+x^2(cosx)
e) y= e^-xcosx = -e^-x(cos x)+ e^-x (-sinx)
f) y=(x^2+1)sinhx = (2x +1) (sinhx)+(x^2+1)(cosh x)
Not (2x + 1) *****
= 2x*sinh(x) + (x^2+1)*cosh(x)
-------------------
Finally, use the quotient rule to differentiate with respect to x, simplifying as far as possible.
a) y= sinx/1+e^-x = 1+e^-x(cosx)-(1-e^x)sinx/(1+e^-x)^2
b) y= lnx/1+x^2 = 1+x^2(1/x)-1+2x(ln x)/(1+x^2)^2


Numeric_Fractions/366514: I am taking classes with the University of Phoenix and this semester I have algebra. The problems is. -2/7x=6/35. I know that you need to multiply both sides by -7/2, and I know that the answer should be -42/70, but they want me to simplify the answer and I just don't undersand where this magical number is supposed to come from. Help!!!!
1 solutions

Answer 261175 by Alan3354(30983) About Me  on 2010-11-05 10:40:13 (Show Source):
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-2/7x=6/35
times -7/2
x = -42/70
----------
42 = 3*14
70 = 5*14
--> x = -3/5


Percentage-and-ratio-word-problems/366378: Hey i would like some help with this: The formula for the surface area of a cylinder is SA= 2πrh+ 2πr^2. The formula for the volume of cylinder is
V = πr^2h. I've gotten where they're in a ratio and solved to 2πrh + πr^2 = h.
Not sure if that is correct.
1 solutions

Answer 261085 by Alan3354(30983) About Me  on 2010-11-04 22:58:16 (Show Source):
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What are you trying to do? What's the question?


Rational-functions/366295: Please help me solve this equation: +f%28x%29+=+sqrt+%28+2-x+%29+.
1 solutions

Answer 261010 by Alan3354(30983) About Me  on 2010-11-04 20:50:13 (Show Source):
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+f%28x%29+=+sqrt+%28+2-x+%29+
0+=+sqrt+%28+2-x+%29+
2-x = 0
x = 2


Trigonometry-basics/366332: Use a graphing calculator to approximate, to three decimal places, the solutions to the equation.?
If there is more than one solution write them separated by commas.
cos x = x^2/3
x=___ , ___
1 solutions

Answer 261008 by Alan3354(30983) About Me  on 2010-11-04 20:48:13 (Show Source):
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I don't have a graphing calculator. I don't plan to get one.


Functions/366288: Given f(x) = -3x + 7, find f(-2)
1 solutions

Answer 260976 by Alan3354(30983) About Me  on 2010-11-04 19:33:10 (Show Source):
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Sub -2 for x.


Linear-systems/366260: 3r-4s=5
4r+3s=15
Solve by elimination
1 solutions

Answer 260975 by Alan3354(30983) About Me  on 2010-11-04 19:26:48 (Show Source):
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3r-4s=5 x3 --> 9r - 12s = 15
4r+3s=15 x4 -->16r +12s = 60
----------------------------- Add
25r = 75
r = 3
Can you finish it?


Travel_Word_Problems/366285: A car and a truck leave the same place to travel on the same road, the truck at 35 m.p.h. and the car at 45 m.p.h. If the car starts 1 hour after the truck, when will it overtake the truck?
1 solutions

Answer 260974 by Alan3354(30983) About Me  on 2010-11-04 19:23:44 (Show Source):
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A car and a truck leave the same place to travel on the same road, the truck at 35 m.p.h. and the car at 45 m.p.h. If the car starts 1 hour after the truck, when will it overtake the truck?
------------------
In 1 hour, the truck goes 35 miles.
The car gains on the truck at 10 mph (45 - 35)
35/10 = 3.5 hours
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It's not possible to find when, since no start time was given, but it's 3.5 hours after the car leaves, 4.5 hours after the truck's departure.


Divisibility_and_Prime_Numbers/366247: divide 6883/7
the answer is ? what is r ?
1 solutions

Answer 260973 by Alan3354(30983) About Me  on 2010-11-04 18:43:33 (Show Source):
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Do you have a calculator? A pencil?
---------
What r?


Triangles/366252: If AB = 4 inches, which does AC equal?


1 solutions

Answer 260972 by Alan3354(30983) About Me  on 2010-11-04 18:42:35 (Show Source):
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insufficient info


Travel_Word_Problems/366262: a car travels 787 km in 11 days. at this rate, how far would it travel in 33 days?
1 solutions

Answer 260971 by Alan3354(30983) About Me  on 2010-11-04 18:41:27 (Show Source):
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It's 3 times as many days.
--> 3 times the distance.


Polynomials-and-rational-expressions/366191: what is the answer to s/6- 2/9=0
1 solutions

Answer 260941 by Alan3354(30983) About Me  on 2010-11-04 16:31:50 (Show Source):
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what is the answer to s/6- 2/9=0
------------
What is the question?
If you mean "What is the value of s?", then
s/6- 2/9=0
s/6 = 2/9
Multiply by 6
s = 12/9 = 4/3


Trigonometry-basics/366058: P(-15/17, -8/17) is found on the unit circle. Find sin(theta) and cos(theta)
1 solutions

Answer 260899 by Alan3354(30983) About Me  on 2010-11-04 14:55:48 (Show Source):
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P(-15/17, -8/17) is found on the unit circle. Find sin(theta) and cos(theta)
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sine = y = -8/17
cosine = x = -15/17