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15390..15419 , 15420..15449 , 15450..15479 , 15480..15509 , 15510..15539 , 15540..15569 , 15570..15599 , 15600..15629 , 15630..15659, >>NextQuadratic_Equations/319980: A square field had 5 meters added to the length and 2 meters to its width. The field then had an area of 130 meters squared. Find the length of a side of the original field. 1 solutions
Answer 229168 by ankor@dixie-net.com(15645) on 2010-07-05 21:59:23 (Show Source):
You can put this solution on YOUR website!A square field had 5 meters added to the length and 2 meters to its width.
The field then had an area of 130 meters squared.
Find the length of a side of the original field.
:
Let x = side of original field
then
(x+5) = the new length
and
(x+2) = the new width
:
L * W = 130
(x+5)(x+2) = 130
FOIL
x^2 + 2x + 5x + 10 = 130
:
x^2 + 7x + 10 - 130 = 0
:
x^2 + 7x - 120 = 0
Factor
(x + 15)(x - 8) = 0
The positive solution is what we want here
x = 8 meters, side of original square
;
:
Check solution by finding the area of the new rectangle
(8+5)*(8+2) = 130
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Percentage-and-ratio-word-problems/319979: If cement, gravel, and sand are to be mixed in the ratio of 3:5:7 respectively, and 5 tons of cement are available, how many tons of the mixture can be made? (Assume that enough gravel and sand are available to use all the available cement.) 1 solutions
Answer 229166 by ankor@dixie-net.com(15645) on 2010-07-05 21:51:11 (Show Source):
You can put this solution on YOUR website!If cement, gravel, and sand are to be mixed in the ratio of 3:5:7 respectively, and 5 tons of cement are available, how many tons of the mixture can be made? (Assume that enough gravel and sand are available to use all the available cement.)
:
We can do it this way, let x = the multiplier
3x:5x:7x
:
Find the multiplier using the cement which was given
3x = 5
x =  is the multiplier
:
Gravel:5 *  =  = 8.33 tons
Sand: 7 *  =  = 11.67 tons
:
Total mixture: 5 + 8.33 + 11.67 = 25 tons
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Functions/319923: The function H described by H(x)=2.75x+71.48 can be used to predict the height, in centimeters, of a woman whose humerus is x cm long. Predict the height of a woman whose humerus is 32 cm long. Please help I am stuck 1 solutions
Answer 229163 by ankor@dixie-net.com(15645) on 2010-07-05 21:36:26 (Show Source):
You can put this solution on YOUR website!The function H described by H(x)=2.75x+71.48 can be used to predict the height,
in centimeters, of a woman whose humerus is x cm long.
Predict the height of a woman whose humerus is 32 cm long.
:
All you have to do is replace x with 32 and do the math
H(32) = 2.75(32) + 71.28
|
Numbers_Word_Problems/319968: Please help me solve the word problem: Find the doubling time for money invested at 3% compounded continuously. 1 solutions
Answer 229160 by ankor@dixie-net.com(15645) on 2010-07-05 21:30:39 (Show Source):
You can put this solution on YOUR website!Find the doubling time for money invested at 3% compounded continuously.
:
The continuous interest formula
 = A
where
P = initial amt (in this problem we will use 1)
r = interest rate in decimal form, (.03)
t = no. of years
A = resulting amt; (in this problem it will be 2)
:
 = 2
using natural logs
 = ln(2)
log equiv of exponents
.03t*ln(e) = ln(2)
Find the nat log of both side. (nat log of e = 1)
.03t = .693
t = 
t = 23.1 yrs to double at 3%
:
:
Confirm this on a calc: enter e^(.03*23.1) results: 1.9997 ~ 2
|
Word_Problems_With_Coins/319875: I have 8 pennies and some quarters, nickels, and dimes. The number of pennies plus nickels equals the number of dimes. I have 3 quarters for every 2 pennies and 3 dimes for every 2 quarters. How many coins are nickels? 1 solutions
Answer 229132 by ankor@dixie-net.com(15645) on 2010-07-05 18:41:15 (Show Source):
You can put this solution on YOUR website!I have 8 pennies and some quarters, nickels, and dimes.
The number of pennies plus nickels equals the number of dimes.
I have 3 quarters for every 2 pennies and 3 dimes for every 2 quarters.
How many coins are nickels?
:
"The number of pennies plus nickels equals the number of dimes."
d = n + 8
:
" I have 3 quarters for every 2 pennies"
q = 3(8/2)
q = 12
:
"and 3 dimes for every 2 quarters."
d = 3(2q)
d = 6q
:
q = 12
therefore
d = 6(12)
d = 72 dimes
:
How many coins are nickels?
d = n + 8
72 = n + 8
72 - 8 = n
n = 64 nickels
|
Expressions-with-variables/319854: I can not figure out how to use elimination method can you please help me?
3r-5s=-7
5r+3s=45
Thank you 1 solutions
Answer 229104 by ankor@dixie-net.com(15645) on 2010-07-05 16:36:21 (Show Source):
You can put this solution on YOUR website!use elimination method
3r - 5s = -7
5r + 3s = 45
:
We are going to multiply each equation by a value that will make the coefficient
of s in each equation to be equal
:
Multiply the 1st equation by 3, multiply the 2nd equation by 5, results
9r - 15s = -21
25r+ 15s = 225
------------------adding eliminates s, find r
34r + 0s = 204
r = 
r = 6
:
Use the 2nd original equation to find s, substitute 6 for r
5(6) + 3s = 45
30 + 3s = 45
3s = 45 - 30
3s = 15
s = 
s = 5
;
:
Check solutions in the original 1st equation
9r - 15s = -21
9(6) - 15(5) =
54 - 75 = -21; confirms our solutions, Make sense to you now?
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Miscellaneous_Word_Problems/319898: How do you do this algebraically?
In a race, the top speed of one car is nine tenths of the top speed of another. After one half hour the faster car is 10 km ahead of the slower car. Find the rate of each car, assuming they started side by side. 1 solutions
Answer 229097 by ankor@dixie-net.com(15645) on 2010-07-05 16:06:55 (Show Source):
You can put this solution on YOUR website!In a race, the top speed of one car is nine tenths of the top speed of another.
After one half hour the faster car is 10 km ahead of the slower car.
Find the rate of each car, assuming they started side by side.
:
Let s = faster car speed
then
.9s = speed of the slower car
:
Write a dist equation; dist = speed * time
:
Fast car dist - slower car dist = 10 km
.5s - .5(.9s) = 10
.5s - .45s = 10
.05s = 10
s = 
s = 200 km/hr is the faster car
then
.9(200) = 180 km/hr is the slower car
:
:
Check solution by finding the dist each traveled in .5 hrs
.5(200) = 100 km
.5(180) = 90 km
------------------
dist dif: 10 km
|
Circles/319662: Points A,B and C lie on a circle and form an equilateral triangle. If AB = 12 what is the circumference of the circle. 1 solutions
Answer 228931 by ankor@dixie-net.com(15645) on 2010-07-04 19:16:28 (Show Source):
You can put this solution on YOUR website!Points A,B and C lie on a circle and form an equilateral triangle.
If AB = 12 what is the circumference of the circle.
:
Draw this out.
The centroid of the equilateral triangle is also the center of circle.
The hypotenuse of the triangle formed by drawing the medians through the
center is also the radius (r).
:
Cos(30) = 
.866r = 6
r = 
r = 6.93
Find the circumference
C = 
C = 43.53
|
Age_Word_Problems/319636: a son is half as old as his father.12 years ago the son was one third as old as his father. how is each now? 1 solutions
Answer 228905 by ankor@dixie-net.com(15645) on 2010-07-04 12:09:27 (Show Source):
You can put this solution on YOUR website!Let s = son's age
Let f = father's age
:
Write an equation for each statement
:
"a son is half as old as his father."
s =  f
:
"12 years ago the son was one third as old as his father."
s - 12 =  (f - 12)
multiply each side by 3, to get rid of the fraction
3(s - 12) = f - 12
3s - 36 = f - 12
3s = f - 12 + 36
3s = f + 24
Replace s with  f, (from the 1st statement)
3(  f) = f + 24
(  f = f + 24
Multiply both sides by 2 to get rid of the fraction, results:
3f = 2(f + 24)
3f = 2f + 48
3f - 2f = 48
f = 48 yrs is father's present age
then
 *48 = 24 yrs is son's present age
:
:
Check solutions in the statement
"12 years ago the son was one third as old as his father."
24 - 12 =  (48 - 12)
12 =  *36, confirms our solutions
|
Miscellaneous_Word_Problems/319408: Find a counterexample to the statement: The cube of a number added to the sum of three times the number and 3 is a prime number. Justify your solution by supporting it with step by step work. 1 solutions
Answer 228904 by ankor@dixie-net.com(15645) on 2010-07-04 11:37:29 (Show Source):
You can put this solution on YOUR website!Find a counterexample to the statement:
The cube of a number added to the sum of three times the number and 3 is a prime number.
:
x = "number"
the equation
y = x^3 + 3x + 3
:
Substituting:
x = 1, then y = 7, a prime number
x = 2, then y = 17, a prime number
however,
x = 3, then y = 39, not a prime number
|
Percentage-and-ratio-word-problems/319453: Soybean meal is 18% protein; cornmeal is 9% protein. How many pounds of each should be mixed together in order to get 360-lb mixture that is 11% protein?
How many pounds of the cornmeal should be in the mixture?
How many pounds of the soybean meal should be in the mixture? 1 solutions
Answer 228854 by ankor@dixie-net.com(15645) on 2010-07-03 21:37:35 (Show Source):
You can put this solution on YOUR website!Soybean meal is 18% protein; cornmeal is 9% protein.
How many pounds of each should be mixed together in order to get 360-lb mixture that is 11% protein?
:
Let x = amt of Soy
the result is to be 360 lb, therefore
(360-x) = amt of corn
:
An amt of protein equation
.18x + .09(360-x) = .11(360)
:
.18x + 32.4 - .09x = 39.6
:
.18x - .09x = 39.6 - 32.4
:
.09x = 7.2
x = 
x = 80 lb of soy
and
360 - 80 = 280 lb of corn
:
:
Check solution in original mixture equation
.18(80) + .09(280) = .11(360)
14.4 + 25.2 = 39.6, confirms our solution
|
Angles/319447: Seven times the complement of an angle is 6 more than the supplement of the angle. What is the measure of the angle? 1 solutions
Answer 228799 by ankor@dixie-net.com(15645) on 2010-07-03 16:33:55 (Show Source):
You can put this solution on YOUR website!Seven times the complement of an angle is 6 more than the supplement of the angle.
What is the measure of the angle?
:
Let x = the angle
we know
(90-x) = complement of x
and
(180-x)= supplement of x
:
The equation for the statement:
"Seven times the complement of an angle is 6 more than the supplement of the angle."
7(90-x) = (180-x) + 6
630 - 7x = -x + 186
630 - 186 = -x + 7x
444 = 6x
x = 
x = 74 degrees is the angle
:
:
YOu can confirm the solution in the original equation
|
Average/319490: The average of 10 students’ test scores was 69. Three students scored 80,60, and 40 respectively. Three other students scored 90, and two students scored 50. The other two students received the same score. What were their scores? 1 solutions
Answer 228798 by ankor@dixie-net.com(15645) on 2010-07-03 16:24:59 (Show Source):
You can put this solution on YOUR website!The average of 10 students’ test scores was 69.
Three students scored 80,60, and 40 respectively.
Three other students scored 90, and two students scored 50.
The other two students received the same score. What were their scores?
:
Let 2x = the two unknown grades
:
Write an equation from the given information:
 = 69
Multiply both sides by 10
80+60+40+270+100+2x = 690
:
2x + 550 = 690
:
2x = 690 - 550
:
2x = 140
x = 
x = 70 are the unknown scores
|
Triangles/319443: Given the perimeter of a triangle is 180 inches. If angles of the triangle are in the ratio 5:6:7. Determine he sides. 1 solutions
Answer 228797 by ankor@dixie-net.com(15645) on 2010-07-03 16:12:32 (Show Source):
You can put this solution on YOUR website!Given the perimeter of a triangle is 180 inches. If angles of the triangle are in the ratio 5:6:7. Determine he sides.
:
Let x = the multiplier
:
5x + 6x + 7x = 180
:
18x = 180
x = 
x = 10 is the multiplier
:
50, 60, 70 are the sides
|
Travel_Word_Problems/319516: It takes one employee 3 hours longer to mow a football field than it does a more experienced employee. Together they can mow the grass in 2 hours. How long does it take for each person to mow the football field working alone? 1 solutions
Answer 228796 by ankor@dixie-net.com(15645) on 2010-07-03 16:02:25 (Show Source):
You can put this solution on YOUR website!It takes one employee 3 hours longer to mow a football field than it does a more experienced employee.
Together they can mow the grass in 2 hours. How long does it take for each
person to mow the football field working alone?
:
Assume they each have a mower
:
Let t = time required by the experienced employee alone
then
(t+3) = time for the other employee
:
Let the completed job = 1
:
A shared work equation
 +  = 1
multiply by t(t+3), results:
2(t+3) + 2t = t(t+3)
:
2t + 6 + 2t = t^2 + 3t
combine like terms on the right
0 = t^2 + 3t - 4t - 6
A quadratic equation
t^2 - t - 6 = 0
Factors to
(t - 3)(s + 2) = 0
positive solution
t = 3 hrs for the experienced guy by himself
and
3 + 3 = 6 hrs for the other guy by himself
:
:
Check solution
 +  =
 +  = 1
|
Geometry_Word_Problems/319494: Let A be the ratio of the volume of a sphere to the volume of a cube each of whose face is tangent to the sphere, and let B be the ratio of the surface area of this sphere to the surface area of the cube. Then find the sum A and B. 1 solutions
Answer 228781 by ankor@dixie-net.com(15645) on 2010-07-03 13:34:59 (Show Source):
You can put this solution on YOUR website!Let A be the ratio of the volume of a sphere to the volume of a cube each of
whose face is tangent to the sphere, and let B be the ratio of the surface
area of this sphere to the surface area of the cube.
Then find the sum A and B.
:
From the description, the sphere is enclosed in a cube
:
Let r = radius of the sphere
then
2r = side of the cube
:
Volume Ratio; sphere/cube
A =  = 
cancel r^3
A =  =  =  =  ; vol ratio
:
Surface area ratio; sphere/cube
B =  =  = 
Cancel 4, and r^2
B = 
:
A + B:  +  =  =
|
Miscellaneous_Word_Problems/319445: twelve people purchased supplies for a ten-day camping trip with the understanding that each of the twelve will get equal daily shares .they are then joined by three more people , but make no further purchases . how long will the supplies then last if the original daily share for each person is not changed ? 1 solutions
Answer 228773 by ankor@dixie-net.com(15645) on 2010-07-03 11:33:20 (Show Source):
You can put this solution on YOUR website!twelve people purchased supplies for a ten-day camping trip with the
understanding that each of the twelve will get equal daily shares .
they are then joined by three more people , but make no further purchases .
how long will the supplies then last if the original daily share for each person is not changed ?
:
We can use a man-day ration (mdr) method
12 men, 10 days, require: 12 * 10 = 120 mdr's were purchased
:
let d = no. of days for 15 men
:
15d = 120
d = 
d = 8 days
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Evaluation_Word_Problems/319127: Tim has $5.03 in quarters, nickels, dimes, pennies, and half-dollars in a desk drawer. He has fice more nickles than quarters, then number of pennies is two-thirds the number of nickles, there are half as many half-dollars as pennies, and half as many dimes as nickels. How many coins of each type does he have?
1 solutions
Answer 228723 by ankor@dixie-net.com(15645) on 2010-07-02 21:47:25 (Show Source):
You can put this solution on YOUR website!Tim has $5.03 in quarters, nickels, dimes, pennies, and half-dollars in a desk drawer.
He has five more nickles than quarters, then number of pennies is two-thirds
the number of nickles, there are half as many half-dollars as pennies,
and half as many dimes as nickels.
How many coins of each type does he have?
:
Write a equation for each statement:
"Tim has $5.03 in quarters, nickels, dimes, pennies, and half-dollars in a desk drawer."
.01p + .05n + .10d + .25q + .50h = 5.03
:
"He has five more nickles than quarters,"
n = q + 5
or
q = n - 5
:
"then number of pennies is two-thirds the number of nickles,"
p =  n
:
"there are half as many half-dollars as pennies,"
h =  p
replace p with  n
h =  *  n
h =  n
:
" half as many dimes as nickels."
d = .5n
:
.01p + .05n + .10d + .25q + .50h = 5.03
get rid of the decimals, multiply by 100
p + 5n + 10d + 25q + 50 = 503
Get everything in terms of n, replace p, d, q, and h
 n + 5n + 10(.5n) + 25(n-5) + 50*  n = 503
multiply by 3, get rid of the fractions
2n + 15n + 30(.5n) + 75(n-5) + 50n = 1509
:
2n + 15n + 15n + 75n - 375 + 50n = 1509
:
157n = 1509 + 375
:
157n = 1884
n = 
n = 12 nickels
:
How many coins of each type does he have?
p:  *12 = 8 pennies
:
h:  *12 = 4 half dollars
:
q: 12 - 5 = 7 quarters
:
d: .5(12) = 6 dimes
:
:
Check the solutions, find the total
.01(8) + .05(12) + .10(6) .25(7) + .50(4) =
.08 + .60 + .60 + 1.75 + 2.00 = 5.03; confirms our solutions
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Quadratic_Equations/319350: Type an exact answer using radicals as needed and use commas to separate answers. What is the solution? w =
w^4 - 2w^2 - 2 = 0 1 solutions
Answer 228715 by ankor@dixie-net.com(15645) on 2010-07-02 20:14:17 (Show Source):
You can put this solution on YOUR website!w^4 - 2w^2 - 2 = 0
:
Find w^2 using the quadratic formula

in this equation
x=w^2, a=1, b=-2, c=-2

:

:
Two solutions

extract the sqrt of 4

Cancel the 2's

Find the square root of both sides
w =  ; a good solution
:
but we also have

extract the sqrt of 4

Cancel the 2's

Find the square root of both sides
w = 
However sqrt of 3 > 1, therefore we have square root of a neg number
:
I'm going to say the exact solution using radicals
w = +  , - 
:
Confirm this with a graph of this equation
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Polynomials-and-rational-expressions/319348: The base of a triangle is 4 inches less than twice the height. The area is 35 inches^2. Find the height and the base. Please help me with this problem. Thank you. 1 solutions
Answer 228679 by ankor@dixie-net.com(15645) on 2010-07-02 16:44:00 (Show Source):
You can put this solution on YOUR website!The base of a triangle is 4 inches less than twice the height.
The area is 35 inches^2. Find the height and the base.
:
Let x = the height
then
(2x-4) = the base
:
The area:  *(2x-4)*x = 35
Multiply both sides by 2, get rid of the fraction
2x^2 - 4x = 2(35)
Arrange as a quadratic equation:
2x^2 - 4x - 70 = 0
simplify, divide by 2
x^2 - 2x - 35 = 0
Factors to
(x-7)(x+5) = 0
The positive solution
x = 7 in is the height
then
2(7) - 4 = 10 in is the base
:
:
Check the area with these values
.5 * 7 * 10 = 35
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Volume/319271: A factory needs a box that has a volume of 6 cubic inches. The width should be 1 inch less than the height and the length should be 3 inches greater than the height. what should the dimensions of the box be? 1 solutions
Answer 228671 by ankor@dixie-net.com(15645) on 2010-07-02 16:17:06 (Show Source):
You can put this solution on YOUR website!A factory needs a box that has a volume of 6 cubic inches.
The width should be 1 inch less than the height and the length should be 3
inches greater than the height.
what should the dimensions of the box be?
:
Let x = the height of the box
then
"width should be 1 inch less than the height"
(x-1) = the width of the box
and
"length should be 3 inches greater than the height."
(x+3) = the length of the box
:
Volume equation
x*(x-1)*(x+3) = 6
x(x^2 + 2x - 3) = 6
x^3 + 2x^2 - 3x = 6
x^3 + 2x^2 - 3x - 6 = 0:
graph this to find the positive solution

x = 1.732 is the height
then
.732 = the width
and
4.732 = the length
;
:
Check solution: 4.732*.732*1.732 = 5.999 ~ 6
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Polynomials-and-rational-expressions/318982: Will someone please help me with these problems.
1) Factors: -8t+xt-24x+3x^2
2) Factors: 9t+wt+9y+yw
3) factors: 5x^2+13xy-6y^2
4) Factor: tu-24t+3t^2-8u 1 solutions
Answer 228668 by ankor@dixie-net.com(15645) on 2010-07-02 15:50:05 (Show Source):
You can put this solution on YOUR website!1) Factors: -8t+xt-24x+3x^2
Group the terms as follows
xt + 3x^2 - 8t - 24x
factor out x and -8
x(t+3x) - 8(t+3x); a -8 changes the sign
Factor out (t+3x)
(t+3x)(x-8)
:
2) Factors: 9t+wt+9y+yw
Group as follows
9t + 9y + wt + yw
Factor out 9 & w
9(t+y) + w(t+y)
Factor out (t+y)
(t+y)(9+w)
:
3) factors: 5x^2+13xy-6y^2
This can be factored as a quadratic, we know that it will be:
(5x___y)(x___y)
The factors of 6 are 2 & 3, choose the signs to satisfy the middle term 13xy
(5x - 2y)(x + 3y); FOIL this to check it
:
4) Factor: tu-24t+3t^2-8u
This is very similar to the 1st problem
See if you can do this exactly the same way
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Quadratic_Equations/319338: how can you determine the nature of roots of this following equation: the square root of 3x suared minus 4 suare roots of 3 equals 0? 1 solutions
Answer 228659 by ankor@dixie-net.com(15645) on 2010-07-02 15:00:50 (Show Source):
You can put this solution on YOUR website! the square root of 3x squared minus 4 square roots of 3 equals 0?
 = 0
add  to both sides
:
Square both sides
3x^2 = 16(3)
Divide both sides by 3
x^2 = 16
x = 
x = 4
:
:
Check solution in original equation
 = 0
extract the square root
 = 0
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Percentage-and-ratio-word-problems/319332: On an exam with q questions, Marie correctly answered 15 of the first 20 but just 1/3 of the rest. If her total score was 50%, what was q? 1 solutions
Answer 228654 by ankor@dixie-net.com(15645) on 2010-07-02 14:32:59 (Show Source):
You can put this solution on YOUR website!On an exam with q questions, Marie correctly answered 15 of the first 20
but just 1/3 of the rest.
If her total score was 50%, what was q?
:
.50q = 15 +  (q-20)
Multiply equation by 3, to get rid of the fraction, results:
3(.5q) = 3(15) + q - 20
:
1.5q - q = 45 - 20
:
.5q = 25
Multiply both sides by 2
q = 50
:
:
Check solution
15 + 1/3(50 - 20) =
15 + 10 = 25 which is 50% of 50
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