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Recent problems solved by 'Earlsdon'

Earlsdon answered: 6281 problems
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Equations/100545: separate the number 78 into three parts so that the second part is twice the first part and the third part is 6 more than the first part
1 solutions

Answer 73197 by Earlsdon(6287) About Me  on 2007-09-26 10:36:42 (Show Source):
You can put this solution on YOUR website!
Let x be the first part, then 2x is the second part and x+6 is the third part.
x + 2x + x+6 = 78
4x+6 = 78
4x = 72
x = 18
2x = 36
x+6 = 24
Check:
18+36+24 = 78


Quadratic_Equations/100465: If the sides of a square picture frame are increased by 5 cm, the area becomes 289 cm^2. Find the length of a side of the original picture frame.
1 solutions

Answer 73148 by Earlsdon(6287) About Me  on 2007-09-25 21:29:17 (Show Source):
You can put this solution on YOUR website!
Let the original side length be x.Then,
%28x%2B5%29%5E2+=+289 Solve for x.
x%5E2%2B10x%2B25+=+289 Subtract 289 from both sides.
x%5E2%2B10x-264+=+0 Solve this quadratic equation for x by factoring.
%28x-12%29%28x%2B22%29+=+0
x-12+=+0 so x+=+12 or
x%2B22+=+0 so x+=+-22 Discard the negative solution as the side length is a positive value.
The original side length is 12 cm.
Check:
%28x%2B5%29%5E2+=+%2812%2B5%29%5E2
17%5E2+=+289


Exponents/100192: This question is from textbook middle grades math
Please so me how to solve..-4 with 2 as an exponent +1 with 3 as an exponent + -15 with 0 as an exponent. I tried -4x-4=16 + 1x1x1=1 + -15 with 0 exponent would be 1? 16+1+1=18 but this answer is wrong book says answer is -14 please help.
1 solutions

Answer 72958 by Earlsdon(6287) About Me  on 2007-09-24 21:22:10 (Show Source):
You can put this solution on YOUR website!
-4%5E2%2B1%5E3%2B%28-15%29%5E0+=+-16%2B1%2B1 = -14
Note:
-%284%29%5E2+=+-%284%29%284%29 = -16 Right? Notice that it is NOT (-4)(-4) which would be +16
1%5E3+=+1%2A1%2A1 = 1 OK?
%28-15%29%5E0+=+1 Why? Because anything raised to the zero power is equal to 1.


Systems-of-equations/100179: I can't understand
Which strategies could be used for solving the following system of equations?
2x + y = 4
x - y = 2
a. Graph both equations on the coordinate plane and find the point of intersection.
b. Solve the first equation for y and then substitute that expression into the second equation.
c. Add the two equations together resulting in an equation with one variable.
d. a, b, and c are all correct
1 solutions

Answer 72956 by Earlsdon(6287) About Me  on 2007-09-24 21:16:48 (Show Source):
You can put this solution on YOUR website!
Which strategy will work?
Which ones have you tried???
In fact, all of the listed strategies will work!
a) Let's do the graph and see how it works.
First, solve each equation for y.
1) 2x+y = 4 Subtract 2x from both sides.
1a) y = -2x+4 (Red line on the graph)
2) x-y = 2 Add y to both sides.
2a) x = y+2 Now subtract 2 from both sides.
x-2 = y or y = x-2 (Green line on the graph)
Now these can be graphed:
graph%28600%2C400%2C-5%2C5%2C-5%2C5%2C-2x%2B4%2Cx-2%29
You can see that the two lines intersect at x = 2, and y = 0 so the solution is: (2, 0)
b) Solve the first equation for y:
2x+y = 4 Subtract 2x from both sides.
y = -2x+4 now substitute this into the 2nd equation:
x-y = 2 Substitute y = -2x+4
x-(-2x+4) = 2
x+2x-4 = 2 Add 4 to both sides.
3x = 6 Divide both sides by 3.
x = 2 Substitute this into the first eqation:
y = -2(2)+4
y = -4+4
y = 0
The solution is:
(2, 0)
Try c on your own and you will see that all three methods will work.


Miscellaneous_Word_Problems/99824: Can you please help me solve this problem: The temperature of 41 degrees Fahrenheit is equivalent to 5 degrees Celius, and the temperature of 77 degrees Fahrenheit is equivalent to 25 degrees Celsius. at what temperature, the degree in Fahrenheit is the same as the degree in Celsius.
Thank you, I most appreciate it

1 solutions

Answer 72665 by Earlsdon(6287) About Me  on 2007-09-23 12:18:38 (Show Source):
You can put this solution on YOUR website!
You could with the conversion formula:
1) F+=+%289%2F5%29C%2B32 or:
2) C+=+%285%2F9%29%28F-32%29
Since you want F = C you can substitute in either equation and solve.
1) F+=+%289%2F5%29F%2B32 Solve for F. Subtract %289%2F5%29F from both sides.
-%284%2F5%29F+=+32 Now multiply both sides by -%285%2F4%29
F+=+-40
2) C+=+%285%2F9%29%28C-32%29 Multiply both sides by 9.
9C+=+5%28C-32%29
9C+=+5C-160 Subtract 5C from both sides.
4C+=+-160 Divide both sides by 4.
C+=+-40
The answer is at -40 degrees the temperature on the Farenheit scale reads the same on the Celsius scale.


Polynomials-and-rational-expressions/99741: Factor completely using integer coefficients:
e) x^4+8x^3-2x^2-16x
f) 2x^6-20x^4-16x^3+160x
j) x^4-x^3-x+1
1 solutions

Answer 72636 by Earlsdon(6287) About Me  on 2007-09-22 22:39:08 (Show Source):
You can put this solution on YOUR website!
Factor completely using integer coefficients:
e) x%5E4%2B8x%5E3-2x%5E2-16x First, factor an x.
x%28x%5E3%2B8x%5E2-2x-16%29 Now factor the parentheses. I know that my factors here will be two binomials of the form:
%28x%5E2%2Bm%29%28x%2Bn%29 where m%2An+=+-16 and nx%5E2+=+8x%5E2 and mx+=+-2x, so m = -2 and n = 8. So the parentheses, when factored, look like:
%28x%5E2-2%29%28x%2B8%29, then the final answer is:
x%5E4%2B8x%5E3-2x%5E2-16x+=+x%28x%5E2-2%29%28x%2B8%29
f) 2x%5E6-20x%5E4-16x%5E3%2B160x First, factor 2x.
2x%28x%5E5-10x%5E3-8x%5E2%2B80%29 Now factor the parentheses. I know my factors here will be two binomials of the form:%28x%5E3%2Bm%29%28x%5E2%2Bn%29 where: m%2An+=+80nx%5E3+=+-10x%5E3 and mx%5E2+=+-8x%5E2 so m+=+-8 and n+=+-10, so the parentheses, when factored, look like:
x%5E3-8%29%28x%5E2-10%29, so far we have:
2x%5E6-20x%5E4-16x%5E3%2B160x+=+2x%28x%5E3-8%29%28x%5E2-10%29 but notice that x%5E3-8 is the difference of two cubes and this can be factored.
x%5E3-8+=+%28x%29%5E3-%282%29%5E3 The difference of two cubes is factored thus:
A%5E3-B%5E3+=+%28A-B%29%28A%5E2%2BAB%2BB%5E2%29 so, in this case:
x%5E3-8+=+%28x-2%29%28x%5E2%2B2x%2B4%29 putting it all together, we have:
2x%5E6-20x%5E4-16x%5E3%2B160x+=+2x%28x-2%29%28x%5E2%2B2x%2B4%29%28x%5E2-10%29
j) x%5E4-x%5E3-x%2B1 Factor as:
%28x%5E3-1%29%28x-1%29 But again, we have the difference of two cubes:%28x%29%5E3-%281%29%5E3, so...
x%5E4-x%5E3-x%2B1+=+%28x-1%29%28x%5E2%2Bx%2B1%29%28x-1%29 or:
x%5E4-x%5E3-x%2B1+=+%28x-1%29%5E2%28x%5E2%2Bx%2B1%29


Rational-functions/99749: I am not sure what I am doing wrong could someone please help me??? Simplify
sqrt1%2F5
1 solutions

Answer 72631 by Earlsdon(6287) About Me  on 2007-09-22 21:51:53 (Show Source):
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Simplify: You don't want to see the square root in the denominator.
sqrt%281%2F5%29 Rewrite as:
%28sqrt%281%29%29%2Fsqrt%285%29 Multiply top & bottom by sqrt%285%29 to rationalise the denominator.
%28sqrt%281%29%29%28sqrt%285%29%29%2F%28sqrt%285%29%29%28sqrt%285%29%29 Simplify.
sqrt%285%29%2F5


Human-and-algebraic-language/99755: This problem was on a pre-employment exam.
If 6 men can do a piece of work in 14 days, how many men are needed to do the work in 21 days?
1 solutions

Answer 72620 by Earlsdon(6287) About Me  on 2007-09-22 21:18:31 (Show Source):
You can put this solution on YOUR website!
Try this!
6 men in 14 days = x men in 21 days. Written as a proportion:
6%2F14+=+x%2F21 Multiply both sides by 21.
6%2821%29%2F14+=+x Simplify.
6%283%29%2F2+=+x
x+=+9
It'll take 9 men to do the same job in 21 days.
//////////////////////////////////////////////
My answer here is incorrect!
Please see the correct answer (#72623) of 4 men given by ankor.


Linear-systems/99709: what are 3 consecutive integer whose sum is -54
1 solutions

Answer 72572 by Earlsdon(6287) About Me  on 2007-09-22 12:46:21 (Show Source):
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Let x be the smallest integer, then the next consecutive integer is x+1 and the next one after that is x+2. The sum of these is:
x%2B%28x%2B1%29%2B%28x%2B2%29+=+-54 Simplify and solve for x.
3x%2B3+=+-54 Subtract 3 from both sides.
3x+=+-57 Divide both sides by 3.
x+=+-19
x%2B1+=+-18
x%2B1+=+-17


Quadratic_Equations/99662: I have a container holding 3/4 litre of liquid. I pour ot 1/3 of the liquid. How much liquid remains in the container?
Can you help me with this one please?
1 solutions

Answer 72525 by Earlsdon(6287) About Me  on 2007-09-21 22:05:36 (Show Source):
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Let's first see how much you poured out:
%281%2F3%29%283%2F4%29+=+1%2F4litre has been removed.
Since you had 3%2F4liter to start with, you now have 3%2F4-1%2F4+=+2%2F4 = 1%2F2litre remaining.


Quadratic_Equations/99657: Fully factorise the following expression. (9m^2 - a^2)
Can you help me with this one please?
1 solutions

Answer 72524 by Earlsdon(6287) About Me  on 2007-09-21 22:00:51 (Show Source):
You can put this solution on YOUR website!
Factor(ise) the following:
%289m%5E2-a%5E2%29 Here, you have the difference of two squares %283m%29%5E2-%28a%29%5E2 which can be factored thus:
%283m%29%5E2-%28a%29%5E2+=+%283m%2Ba%29%283m-a%29


Miscellaneous_Word_Problems/99118: I have never been good at word problems. I have been trying these problems since Sunday. It's due today. Here is the question "Kinetic energy of a particle of mass (m) is found by taking one-half of the product of the mass (m) and the square of the velocity (v). Write an expression for the kinetic energy of a particle.
1 solutions

Answer 72129 by Earlsdon(6287) About Me  on 2007-09-19 11:01:06 (Show Source):


Radicals/98904: Could you please help me solve this question: In a right triangle, the length of the hypothenuse is 5 and the length of the legs is 3, determine the tangents of all three angles. Also find the distance between (1,3) and (5,6).
Thank you, very much.
1 solutions

Answer 71987 by Earlsdon(6287) About Me  on 2007-09-18 11:17:29 (Show Source):
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1) "In a right triangle, the length of the hypotenuse is 5 and the length of the legs is 3" ???
This cannot be true!
Remember that in any right triangle, the length of the hypotenuse squared is equal to the sum of the squares of the two legs. If the dimensions of the right triangle are truly what you have written, then we have, courtesy of Pythagoras:
5%5E2+=+3%5E2+%2B+3%5E2
25+=+9%2B9
25+=+18 No way!
Perhaps you meant to write "...and the length of legs are 3 and 4,..."
If so, then we have a right triangle.
The tangent of the three angles are:
Tangent 90 degrees is undefined.
The tangent of the other two angles, A and B, are:
Tan+A+=+3%2F4
Tan+B+=+4%2F3
2)
Find the distance between the two points (1, 3) and (5, 6)
You can use the distance formula: d+=+sqrt%28%28x%5B2%5D-x%5B1%5D%29%5E2%2B%28y%5B2%5D-y%5B1%5D%29%5E2%29
Substituting x%5B1%5D+=+1, x%5B2%5D+=+5, y%5B1%5D+=+3, and y%5B2%5D+=+6
d+=+sqrt%28%285-1%29%5E2%2B%283-6%29%5E2%29
d+=+sqrt%284%5E2%2B%28-3%29%5E2%29
d+=+sqrt%2816%2B9%29
d+=+sqrt%2825%29
d+=+5 Notice that we use only the positive answer from the square root because distance is a positive (usually) value.


Graphs/98840: This question is from textbook
one question: about finding center and radius (circle graph) :
+3x%5E2+%2B+3y%5E2+-+6x+%2B+12y=+0+


i did this:
(3x^2 -6x) + (3y^2 +12y)=0
then I complete the square:
-6/2 = -3^2=9 and 12/2 =6^2=36
then:
(3x^2-6x+9) + (3y^2+12y+36)= 9+36
(3x-3)^2 + (3y +6)^2 =45
factor:
3(x-1) + 3(y+2)= 45
i got the answer for center:
C(1,-2)
and the answer to the raduis is square root of 5
which i dont know how they got it.

thank you




1 solutions

Answer 71911 by Earlsdon(6287) About Me  on 2007-09-17 21:54:20 (Show Source):
You can put this solution on YOUR website!
Well, your error is found in the step..."completing the square"
Let's go over that:
3x%5E2-6x%2B3y%5E2%2B12y+=+0 then you said ..."complete the square", but before you do that, you should factor out a 3 then divide through by 3 and you will get:
3%28x%5E2-2x%2By%5E2%2B4%29+=+0 Divide both sides by 3.
x%5E2-2x%2By%5E2%2B4y+=+0 Now you complete the square when the coefficients of the x%5E2 and y%5E2 terms are equal to 1.
%28x%5E2-2x%2B1%29%2B%28y%5E2%2B4y%2B4%29+=+1%2B4 Factor the trinomials.
%28x-1%29%5E2%2B%28y%2B2%29%5E2+=+5 Now compare this with the standard form for a circle of radius r and center at (h, k).
%28x-h%29%5E2%2B%28y-k%29%5E2+=+r%5E2and you can see that h = 1, k = -2, and r%5E2+=+5
The center (h, k) is at (1, -2) and the radius is r+=+sqrt%285%29


Polygons/98833: Two poles are 33 feet and 48 feet high, respectively. A wire is strung from the top of one pole to the top of the other. How long is the wire if the poles are 36 feet apart?
1 solutions

Answer 71899 by Earlsdon(6287) About Me  on 2007-09-17 21:26:30 (Show Source):
You can put this solution on YOUR website!
Assuming that there is no sag in the wire betwwen the two poles (not a realistic situation), then we can make a right triangle in which the wire represents the hypotenuse, the base of the triangle is represented by the distance between the two poles (36ft.) and the height of the triangle is simply the difference between the heights of the two poles (48ft. - 33ft. = 15ft.).
Now you can apply the pythagorean theorem to find the length of the hypotenuse (the length of the wire (W))
W%5E2+=+15%5E2%2B36%5E2
W%5E2+=+225+%2B+1296
W%5E2+=+1521 Take the square root of both sides.
W+=+39ft.
The length of the wire is 39 feet.


Geometry_Word_Problems/98505: A circular sheet of paper of radius 6 cm is cut into three equal sectors, and each sector is formed into a cone with no overlap. What is the height in centimeters of each cone?
1 solutions

Answer 71676 by Earlsdon(6287) About Me  on 2007-09-16 14:16:40 (Show Source):
You can put this solution on YOUR website!
We could find the height of the resulting cone if we knew their slant-height and radius.
Starting with the circular sheet of paper whose radius (R) is 6 cm. If you divide this into three equal sectors to form the cones, then each cone will have a slant-height equal to the radius of the original circle, right?
Now the circumference of the base of each cone will be equal to one third of the circumference of the original circle.
The circumference (C) of the original circle is:
C+=+2%28pi%29R and, of course, you know that R is 6 cm, so...
C+=+12%28pi%29 Divide both sides by 3 to find one third of this.
C%2F3+=+4%28pi%29 and this is the circumference (c) of the cone base.
From this we can find the radius (r) of the cone base because c+=+2%28pi%29r but this is equal to 4%28pi%29. So we can write:
2%28pi%29r+=+4%28pi%29 Simplifying, we get:
2r+=+4 and so...
r+=+2 this is the radius of the cone base.
Now we can use the Pythagorean theorem to find the cone height using the slant-height of the cone (6 cm) as the hypotenuse of a right triangle and the radius of the cone base (2 cm) as the base of a right triangle.
6%5E2+=+2%5E2+%2B+h%5E2 where h is the height of the cone.
36+=+4+%2B+h%5E2 Subtract 4 from both sides.
h%5E2+=+32 Take the square root of both sides.
h+=+5.657cm. This is the height of the cone to the nearest thousandth.


Equations/98468: This question is from textbook
Can you please help me with this problem !!! I've been stuck on it for a long time!!
I have to solve for "x".
+%28x-5%29%2Fa+%2B+1+=+b+
I tried this...
a(x-5/a) + a(1) = a(b)
x-5 + a = ab
x + a = 5 + ab
x = 5 + ab - a
but i don't think that that's right. =/
1 solutions

Answer 71649 by Earlsdon(6287) About Me  on 2007-09-16 09:57:52 (Show Source):
You can put this solution on YOUR website!
You might ask yourself why you don't think that your answer is right?
%28x-5%29%2Fa%2B1+=+b Multiply both sides by a.
x-5%2Ba+=+ab Subtract a from both sides.
x-5+=+ab-a Finally. add 5 to both sides.
x+=+5%2Bab-a which is precisely what you got for an answer!
This could also be written as:
x+=+a%28b-1%29%2B5


Money_Word_Problems/98428: A manager sell peanuts for $2.50 per pound. He wants to mix cashews that sell for $5.00 a pound with the peanuts to create 30 pounds of a mixture that sells for $4.00 a pound. How many pounds of each nut are needed.
please show me how to set this up and solve it
1 solutions

Answer 71600 by Earlsdon(6287) About Me  on 2007-09-15 19:02:46 (Show Source):
You can put this solution on YOUR website!
Well, you can start by assigning variables to the unknown quantities.
Let P = the number of pounds of peanuts at $2.50 per pound.
Let C = the number of pounds of cashews at $5.00 per pound.
From the problem description, you are told that P + C = 30 pounds and this mixture will cost $4.00 per pound.
We have enough information to set up the necessary equation, but there are two unknowns and only one equation. We need to reduce the number of unknowns to only one.
$2.50(P) + $5.00(C) = $4.00(30) but you are also told that:
P + C = 30 which can be written as C = 30 -P so we'll replace the C with 30-P.
$2.50(P) + $5.00(30-p) = $4.00(30) Now you can simplify this and solve for P.
2.5P+5(30-P) = 4(30)
2.5P+150-5P = 120 Combining like-terms, we get:
-2.5P = -30 Divide both sides by -2.5
P = 12 You will need 12 pounds of peanuts.
C = 30-P
C = 30-12
C = 18 You will need 18 pounds of cashews.
Check:
Cost of 12 pounds of peanuts + cost of 18 pounds of cashews = cost 0f 30 pounds of mixed nuts at $4.00 per pound.
$2.50(12) + $5.00(18) = $4.00(30)
$30.00 + $90.00 = $120
$120.00 = $120.00


expressions/98136: was wandering if any one could help me with this
1/6f-5=1
-36 is this right, thank you for you time.
1 solutions

Answer 71369 by Earlsdon(6287) About Me  on 2007-09-13 22:59:32 (Show Source):
You can put this solution on YOUR website!
'twould be most helpful if you were to use parentheses to remove any ambiguity in your problem statement!
I was wondering too...is your problem:
1%2F%286f-5%29+=+1? written as 1/(6f-5) = 1 or is it:
%281%2F6f%29-5+=+1? written as (1/6f)-5 = 1
I'm going to assume that it's the second equation.
%281%2F6f%29-5+=+1 Add 5 to both sides of the equation.
1%2F6f+=+6 Multiply both sides by 6f.
1+=+6%286f%29
1+=+36f Finally, divide both sides by 36.
1%2F36+=+f


Square-cubic-other-roots/98086: what is the 5th square root of 1.63. I Cannot find this button on my calculator!
1 solutions

Answer 71340 by Earlsdon(6287) About Me  on 2007-09-13 21:16:50 (Show Source):
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Find the fifth root (not the 5th square root) of 1.63.
Most calculators have a square root key but not the cube root, fourth root, etc.
To find a higher root than square root, it is good to know that the square root of a number can be written as:
sqrt%28x%29+=+x%5E%281%2F2%29
In general, the nth root of a number, x, can be written: x%5E%281%2Fn%29
So you can write the 5th root of 1.63 as:
1.63%5E%281%2F5%29 and this can be put in your calculator using the caret sign (^)
So enter the 1.63 then the caret (^) then (1/5) followed by the = or ENTER key and you should get: 1.10264959142


Angles/97938: This question is from textbook intro alg blitzer
The angle's measure is three times that of its supplement. I just need a formula to work the solution out. ty
1 solutions

Answer 71252 by Earlsdon(6287) About Me  on 2007-09-13 11:09:20 (Show Source):
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If the angle is A, then its supplement is (180-A), so three times ts supplement would be 3(180-A), so you can write:
A = 3(180-A)


Equations/97695: This question is from textbook intro alg blitzer
Solve for h.

S= 2 Pi rh + 2 Pi r(to the 2nd power)
Here's what I got.
S = h
---------
2 Pi r + 2 Pi r(to the 2nd power)
Am I missing a step or is this correct?

1 solutions

Answer 71079 by Earlsdon(6287) About Me  on 2007-09-12 10:56:12 (Show Source):
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Solve for h:
S+=+2%28pi%29rh%2B2%28pi%29r%5E2 Subtract 2%28pi%29r%5E2 from both sides.
S-2%28pi%29r%5E2+=+2%28pi%29rh Now divide both sides by 2%28pi%29r
%28S-2%28pi%29r%5E2%29%2F2%28pi%29r+=+h


Travel_Word_Problems/97604: Science and medicine. The equation h=-16t^2+112t gives the height of an
arrow, shot upward from the ground with an initial velocity of 112 ft/s, where t is the time after the arrow leaves the ground. Find the time it takes for the arrow to reach a height of 180 ft.Solve to the nearest thousandth.
Please help me. I need to show all of the work and I am stumped. I have a horrible problem with word problems.
Thank you very much for your help.
1 solutions

Answer 71012 by Earlsdon(6287) About Me  on 2007-09-11 21:21:08 (Show Source):
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Well, you have given the of height (h) as a function of time (t) as:
h%28t%29+=+-16t%5E2%2Bv%5B0%5Dt%2Bh%5B0%5D where v%5B0%5D+=+112ft/sec, and h%5B0%5D+=+0.
So what you are asking for is at what time, t, will h = 180 ft? Right?
Substituting h = 180, you can solve for t.
180+=+-16t%5E2%2B112t Subtract 180 from both sides.
-16t%5E2%2B112t-180+=+0 Simplify this by factoring a -4.
-4%284t%5E2-28t%2B45%29+=+0 Factor trinomial in the parentheses.
-4%282t-5%29%282t-9%29+=+0 Apply the zero products principle.
2t-5+=+0 or 2t-9+=+0 then:
2t+=+5 or 2t+=+9 so...
t+=+2.5 or t+=+4.5
The answer to the question..."At what time will the arrow reach a height of 180 ft?"
It will reach a height of 180 ft in 2.5 seconds on the way up and again at 4.5 seconds on the way down.


Proofs/97605: I want to know the next four letters of this pattern: T,F,S,N,E,T
1 solutions

Answer 71002 by Earlsdon(6287) About Me  on 2007-09-11 21:01:38 (Show Source):
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Here's a guess!
T, F, S, N, E. T, F, S, N, T,
What do they mean...my guess is they are the initial letters of the odd integers beginning with 3.
T = 3
F = 5
S = 7
N = 9
E = 11
T = 13
F = 15
S = 17
N = 19
T = 21


Finance/97502: This question is from textbook
Heres the question:
A farmer wants to buy 100 animals for $100.00 (must buy at least one of them)
Horses-$5.00
Cows-$3.00
Chicks-.50
How many horses,cows and chicks does the farmer need to have 100 and 100.00?
1 solutions

Answer 70951 by Earlsdon(6287) About Me  on 2007-09-11 18:28:20 (Show Source):
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This problem involves diophantine equations, where you have more unknowns than equations.
The solutions, however, are limited by the fact that the unknowns must be integers, i.e. whole cows, whole horses, etc.
We can set up two equations as follows: H = number of horses, C = number of cows, and ch = number of chicks.
From the problem description, we can write:
H+C+ch = 100 The total number of animals is 100.
($5)H+($3)C+($0.50)ch = $100 The total amount the farmer spends.
The two equations are:
1) H+C+ch = 100
2) 5H+3C+0.5ch = 100 Multiply this equation by 2 and subtract equation 1) from the result.
1) H+C+ch = 100
2a) 10H+6C+ch = 200
--------------------
3) 9H+5C = 100 Subtract 9H from both sides.
3a) 5C = 100-9H Now divide both sides by 5.
3b) C = 20-(9/5)H Now C can only be an integer if H is a multiple of 5. Let's try H = 5.
3c) C = 20-(9/5)(5)
C = 20 - 9
C = 11 This is one possibility. Now let's try H = 10
3d) C = 20 - (9/5)(10)
C = 20 - 18
C = 2 This is another possibility.
H cannot be greater than 10 otherwise you would end up with C being a non-integer or a negative number.
So, if C = 11 when H = 5, then ch = 100-11-5 = 84 - the number of chicks.
Let's check this solution.
H+C+ch = 100
5+11+84 = 100 and...
5($5) + 11($3) + 84($0.50) = $25 + $33 + $42 = $100 This is a valid solution!
Now if C = 2 when H = 10, then ch = 100-2-10 = 88 - the number of chicks.
Let's check this solution.
H+C+ch = 100
10+2+88 = 100 and...
10($5)+2($3)+88($0.50) = $50+$6+$44 = $100 This solution is also valid!
The two solutions are:
1) 5 horses, 11 cows, and 84 chicks.
2) 10 horses, 2 cows, and 88 chicks.


Miscellaneous_Word_Problems/97428: iN YOUR ECONOMICS CLASS YOU HAVE SCORES OF 68, 82, 87, AND 89 ON THE FIRST FOUR OF FIVE TEST. TO GET A GRADE OF B THE AVERQAGE OF THE FIRST FIVE TEST SCORES MUST BE GREATER THAN OR EQUAL TO 80 AND LESS THAN 90. SOLVE AN INEQUALITY TO FIND THE RANGE OF THE SCORES THAT YOU NEED ON THE TEST TO GET A B
1 solutions

Answer 70905 by Earlsdon(6287) About Me  on 2007-09-11 11:40:55 (Show Source):
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To find the average score (A) of the first five tests, you'll add the scores and divide by 5.
A+=+%2868%2B82%2B87%2B89%2Bx%29%2F5 where x is the score on the fifth test.
Now you need this average (A) to be at least 80 (A+%3E=+80) but less than 90 (A+%3C+90).
You can write the inequality thus:
80+%3C=+%28%2868%2B82%2B87%2B89%2Bx%29%2F5%29+%3C+90 To solve this, you'll simplify the numerator.
80+%3C=+%28%28326%2Bx%29%2F5%29+%3C90 Now you'll multiply everything by 5.
%285%2980+%3C=+%28326%2Bx%29+%3C+%285%2990 Simplify.
400+%3C=+%28326%2Bx%29+%3C+450 Now you'll subtract 326 from everything.
%28400-326%29+%3C=+x+%3C+%28450-326%29 Simplify.
74+%3C=+x+%3C+124 Read this as: x is at least 74 but less than 124.
The range of scores needed to get a B average is at least 74 but less than 124.


Miscellaneous_Word_Problems/97186: The fifth, fifteenth & fiftieth parts of a number together make 43. Find the number.
1 solutions

Answer 70768 by Earlsdon(6287) About Me  on 2007-09-10 12:10:56 (Show Source):
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Let n be the required number. From the problem description, you can write:
%28n%2F5%29%2B%28n%2F15%29%2B%28n%2F50%29+=+43 Add the fractions, the LCD is 150.
%2830n%2B10n%2B3n%29%2F150+=+43 Simplify.
43n%2F150+=+43 Multiply both sides by 150.
43n+=+43%28150%29 Divide both sides by 43.
n+=+150


Equations/97151: Find two consecutive odd integers such that 3 times the first integer
is 5 more than twice the second. Please help me figure this one out.
I also would like to no if there is a way that I can check to see if the question I am about to ask is not already been answered somewhere? Can I search the web site some how? Could you tell me how if it is possible?
Thank you
1 solutions

Answer 70728 by Earlsdon(6287) About Me  on 2007-09-09 22:14:44 (Show Source):
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1) Let x be the first odd integer, then x+2 will be the next consecutive odd integer.
From the problem description, you can write:
3x = 2(x+2)+5 Apply the distributive property to the right side.
3x = 2x+4+5 Simplify.
3x = 2x+9 Subtract 2x from both sides.
x = 9
The two integers are 9 and 11
Check:
3(9) = 2(11)+5
27 = 22+5
27 = 27
2) I don't know of an easy way to see if a similar problem to one you want help with has already been answered. You could try clicking on "Recent problems solved by all" and do a manual search but that could be quite time-consuming.


Distributive-associative-commutative-properties/97039: How do you factor x^3+8?
1 solutions

Answer 70625 by Earlsdon(6287) About Me  on 2007-09-09 14:45:13 (Show Source):
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Factor:
x%5E3%2B8 Do you recognise this as the sum of two cubes?
x%5E3%2B8+=+%28x%29%5E3%2B%282%29%5E3...but of course!
The sum of two cubes can be factored thus:
A%5E3%2BB%5E3+=+%28A%2BB%29%28A%5E2-AB%2BB%5E2%29
In your problem, A = x and B = 2, so...
x%5E3%2B8+=+%28x%2B2%29%28x%5E2-2x%2B4%29 and we're done!
Let's check the solution by multiplying the two factors, using FOIL.
%28x%2B2%29%28x%5E2-2x%2B4%29+=+x%5E3-2x%5E2%2B4x%2B2x%5E2-4x%2B8 Simplify by combining like-terms.
x%5E3%2B8+=+x%5E3%2B8


Travel_Word_Problems/96972: A bike race consists of two segments whose total length is 90 km. The first segment is covered at 10 kph and takes 2 hours longer to complete than the second segment, which is covered at 25 kph. How long is each segment?
I have tried setting it up as t/25 = (t+2)/10 but for some reason I can't figure out the algebra.
Thanks!
1 solutions

Answer 70600 by Earlsdon(6287) About Me  on 2007-09-09 11:41:04 (Show Source):
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From your equation, it appears that you assumed that the two segments were the same distance, but there is nothing in the problem to support this assumption.
So, back to basics:
d%5B1%5D+=+r%5B1%5Dt%5B1%5D and...
d%5B2%5D+=+r%5B2%5Dt%5B2%5D
We know that:
r%5B1%5D+=+10 and...
r%5B2%5D+=+25
t%5B1%5D+=+t%5B2%5D+%2B+2 and we also know that:
d%5B1%5D%2Bd%5B2%5D+=+90 So we can write:
d%5B1%5D+=+10t%5B1%5D
d%5B2%5D+=+25t%5B2%5D aagh...to many variables! Let's replace t%5B1%5D with t%5B2%5D%2B2 and replace d%5B2%5D with 90-d%5B1%5D, so now we have:
d%5B1%5D+=+10%28t%5B2%5D%2B2%29 and
90-d%5B1%5D+=+25t%5B2%5D Solve this for d%5B1%5D
d%5B1%5D+=+90-25t%5B2%5D...but, of course, d%5B1%5D+=+d%5B1%5D, so...
10%28t%5B2%5D%2B2%29+=+90-25t%5B2%5D Good, now we have one variable t%5B2%5D, so let's solve for it.
10t%5B2%5D%2B20+=+90-25t%5B2%5D
35t%5B2%5D%2B20+=+90
35t%5B2%5D+=+70 and...
t%5B2%5D+=+2hrs. Now we can find d%5B1%5D and d%5B2%5D
d%5B1%5D+=+10%28t%5B2%5D%2B2%29
d%5B1%5D+=+10%282%2B2%29
d%5B1%5D+=+40km and...
d%5B2%5D+=+90-d%5B1%5D
d%5B2%5D+=+90-40
d%5B2%5D+=+50km
Check:
Total distance is d%5B1%5D%2Bd%5B2%5D+=+40%2B50 = 90km


Exponents/96847: how do you answer this question? (2^4)(2^3) I tink the answer may be negative exponent law = 1/2^1
1 solutions

Answer 70470 by Earlsdon(6287) About Me  on 2007-09-08 11:52:22 (Show Source):
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Simplify:
%282%5E4%29%282%5E3%29 When multiplying quantities with exponents, if the bases are the same (base is 2 in this case) then you add the exponents:
%282%5E4%29%282%5E3%29+=+2%5E%28%284%2B3%29%29 = 2%5E7