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Linear-systems/446133: Solve the system of equations.
2x+8y+z=17
-x+y+4z=-7
x+4y+4z=-2

I would appreciate the help. thank you
1 solutions

Answer 307194 by mananth(12270) About Me  on 2011-05-06 21:25:25 (Show Source):
You can put this solution on YOUR website!
2x+8y+1 z=17--------------1
-1x+1y+4z=-7--------------2
1x+4y+4z=-2--------------3

consider equation 1 &2 Eliminate y
Multiply 1 by 1
Multiply 2 by -8
we get
2x+8y+z =17
8x-8y-32z=56
Add the two
10x-31z=73 -------------4
consider equation 2 & 3 Eliminate y
Multiply 2 by-4
Multiply 3 by 1
we get
4x-4y-16z=28
x+4y+4z=-2
Add the two
5x-12z=26 -------------5 5
Consider (4) & (5) Eliminate x
Multiply 4 by 1
Multiply (5) by -2
we get
10x-31z=73
-10x+24z=-52
Add the two
-7z=21
/ -7
z=-3
Plug the value of z in 5
5x+36=26
5x=-10
x=-2
plug value of x & z in 1
-4+8y-3 =17
8y=4+3+17
y=24
m.ananth@hotmail.ca


Graphs/446059: Can you help me find the x- and y-intercepts and graph the equation plotting the intercepts? -2x + 3y = -15
Thank you so much!

1 solutions

Answer 307192 by mananth(12270) About Me  on 2011-05-06 21:10:03 (Show Source):
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-2x + 3y = -15
3y=2x-15
y =2x/3-5
y intercept, x=0
when x=0 y = -5 (0,-5)
x Intercept
when y=0, x =15/2 ( 15/2,0)
Plot the points draw the line



Travel_Word_Problems/446063: two cars start from the same point and travel in opposite directions. One car goes 15 mph faster than the other. In the 3 hours the cares are 315 miles apart. What is the rate of the faster car?
1 solutions

Answer 307191 by mananth(12270) About Me  on 2011-05-06 20:59:51 (Show Source):
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Car I x mph
Car II x+ 15
..
They are going away from each other.

So add up their speed.

combined speed = x+x+15
(2x+15)
Time = 3 hours
Distance = 315 miles
Distance = speed * time
(2x+15)*3=315
6x+45=315
6x=315+-45
6x=270
/6
x=45 mph Car I
Car II 45+15=60 mph



Rational-functions/446074: ok in my book im haven trouble with the problem 3x+x/3=5
1 solutions

Answer 307190 by mananth(12270) About Me  on 2011-05-06 20:53:09 (Show Source):
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3x+x/3=5
multiply by 3
9x+x=5*3
10x=15
/10
x=15/10
x=3/2


Mixture_Word_Problems/446083: how many gallons of 70% antifreeze should be mixed with 10 gallons of 30% antifreeze to obtain 45% antifreeze.
1 solutions

Answer 307188 by mananth(12270) About Me  on 2011-05-06 20:51:05 (Show Source):
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------ percent ---------------- quantity
Antifreez1 I 80---------------- 40 gallons
Antifreeze II 10----------------x gallons
Total 30 ----------------40+x gallons
30*10+70*x=45(10+x)
300+70x=450+45x
70x-45x=450-300
25x=150
/25
x=6 gallons 70 % Antifreeze II


Travel_Word_Problems/446084: If train a is traveling at 55mph and a second train is traveling at 110mph, how many more miles would the first train travel in 3 hrs?
1 solutions

Answer 307186 by mananth(12270) About Me  on 2011-05-06 20:44:49 (Show Source):
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110-55 = 55 mph is the difference in speed
55*3= 165 miles ahead


Mixture_Word_Problems/446085: how many gallons 65%antifreeze and how many 20% antifreeze should be mixed up to obtain 50 gallons of 56% mixture of antifreeze?
1 solutions

Answer 307185 by mananth(12270) About Me  on 2011-05-06 20:42:57 (Show Source):
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percent ---------------- quantity
Antifreeze I 65----------------x gallons
Antifreeze II 20 ----------------50-x gallons
Total 56.00% ----------------50 gallons

65x+20(50-x)=56 *50
65x+1000-20x=2800
65x-20x=2800-1000
45x=1800
/45
x=40 gallons 65.00%
10 gallons 20.00%


Travel_Word_Problems/446098: a person rowed her boat upstream a distance of 5 miles and then back to the starting point. The total time of the trip was 6 hours. If the rate of the current was 2 miles per hour, find the average speed of the boat in still water
1 solutions

Answer 307184 by mananth(12270) About Me  on 2011-05-06 20:36:32 (Show Source):
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Boat speed x
current speed 2

against current x-2 mph
with current x+ 2 mph

Distance= 5 miles

Time against + time with = 6 hours
t=d/r
Find the roots of the equation by quadratic formula

a= 6, b= -10, c= -24,

b^2-4ac=100+576
b^2-4ac=676
sqrt(676)=26
x=%28-b%2B-sqrt%28b%5E2-4ac%29%29%2F%282a%29
x1=%28-b%2Bsqrt%28b%5E2-4ac%29%29%2F%282a%29
x1=(10 +26)/12
x1=3
x2=(10-26)/12
x2= -1.33
Ignore negative value
3 mph speed of boat in still water


Travel_Word_Problems/446104: A ladder is resting against a wall. The top of the ladder touches the wall at a height of 9ft. Find the length of the ladder if the length is 3ft more than its distance from the wall.
1 solutions

Answer 307183 by mananth(12270) About Me  on 2011-05-06 20:29:08 (Show Source):
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wall ladder distance =x
length of ladder = x+3
height touching the wall = 9
(x+3)^2=x^2+9^2
x^2+6x+9=x^2+81
6x=81-9
6x=72
/6
x=12 feet
ladder ===>x+3= 12+3=15 feet
m.ananth@hotmail.ca


Travel_Word_Problems/446106: A boat is 92 feet from the base of a cliff. If the distance from the top of the cliff to the boat is 23 less than twice the height of the cliff to the water, find the height of the cliff. Round to the nearest tenth of afoot if necessary.
1 solutions

Answer 307182 by mananth(12270) About Me  on 2011-05-06 20:23:55 (Show Source):
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let height of cliff be x
distance from cliff to boat = 2x-3
distance from boat to cliff on ground = 92
Use Pythagoras theorem
(2x-3)^2=x^2+92^2
4x^2-12x+9=x^2+8464
3x^2-12x-8455=0
a= 3, b= -12, c= -8455

b^2-4ac=144+101460
b^2-4ac=101604
sqrt(101604)=318.75
x=%28-b%2B-sqrt%28b%5E2-4ac%29%29%2F%282a%29
x1=%28-b%2Bsqrt%28b%5E2-4ac%29%29%2F%282a%29
x1=(12+318.75)/6
x1= 55.13
x2=(12-318.75)/6
x2=-51.13
Ignore negative value
Height = 55.13 ft
m.ananth@hotmail.ca


Expressions-with-variables/446112: solving systems Using Elimination : 2x-3y=-11
3x+2y=29
1 solutions

Answer 307180 by mananth(12270) About Me  on 2011-05-06 20:12:11 (Show Source):
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2x-3y= -11 .............1
3x+2y=29 .............2
Eliminate y
multiply (1)by 2
Multiply (2) by 3
4x-6y=-22
9x+6y= 87
Add the two equations
13x=65
/13
x= 5
plug value of x in (1)
2x-3y=-11
10-3y=-11
-3y=-11-10
-3y=-21
y=7


Word_Problems_With_Coins/445908: a toy savings bank contains $17.30 consisting of nickels, dimes and quarters. the number of dimes exceeds twice the number of nickels by 3 and the number of quarters is 4 less than 5 times the number of nickels. how many quarters are in the bank?
1 solutions

Answer 307062 by mananth(12270) About Me  on 2011-05-06 07:28:22 (Show Source):
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nickels 5 x
dimes 10 (2x+3)
quarters 25 (5x-4)

Value= 1730

5x+20x+30+125x-100=1730
150x+30 =1830
150x=1830-30
150x=1800
/150
x=12 nickels 15 2x+3 dimes = 27
5x-4 = 56 quarters


Systems-of-equations/445829: Determine whether the graphs of the two equations are perpendicular.
x+2y=7
2x+4Y=3
are the graphs of the given equations perpendicular? Y-N
1 solutions

Answer 307055 by mananth(12270) About Me  on 2011-05-06 05:52:45 (Show Source):
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x+2y=7
2y=-x+7
y=-x/2+7
..
2x+4y=3
4y=-2x+3
y=-2x/4 +3
y=-x/2+3
The slopes are same.
so they are not perpendicular


Travel_Word_Problems/445844: A boat travels 10 km upstream and 10 km back. The time for the round trip is 10 hours. The speed of the stream is 4 km/hr. What is the speed of the boat in still water?
1 solutions

Answer 307054 by mananth(12270) About Me  on 2011-05-06 05:09:54 (Show Source):
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Boat speed x
current speed 4

against current x-4 mph
with current x+ 4 mph

Distance= 10 miles

Time agianst + time with = 10 hours
t=d/r
10/(x +4)+10/(x -4)=10
LCD =(x -4)(x+4)
10*(x-4)+10x+4)=10
10x-40+10x+40=10(x ^2-16)
20x=10x^2-160
10x ^2-20x-160 =0
Find the roots of the equation by quadratic formula

a= 10 b= -20 c= -160

b^2-4ac=400+6400
b^2-4ac=6800
sqrt(6800)=82.46
x=%28-b%2B-sqrt%28b%5E2-4ac%29%29%2F%282a%29
x1=%28-b%2Bsqrt%28b%5E2-4ac%29%29%2F%282a%29
x1=(20+82.46)/20
x1=5.12
x2=(20-82.46)/20
x2= -3.12
Ignore negative value
speed = 5.12 mph


Mixture_Word_Problems/445863: If a merchant has two types of tea, one work $2.70 per kilogram and the other worth $3.00 per kilogram, how many kilograms of each type should the merchant use in order to produce 30 kilograms of a blend that is worth $2.95 per kilogram?
1 solutions

Answer 307053 by mananth(12270) About Me  on 2011-05-06 04:59:09 (Show Source):
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Price ----------------quantity
Tea Type I 2.7----------------x pounds
Tea Type II 3----------------30-x pounds
Total 2.95----------------30
2.7x+3(30-x)=2.95*30
2.7x+90 -3x=88.5
2.7x-3x=88.5-90
-0.3x=-1.5
/-0.3
x=5 pounds$ 2.70
25 pounds $3.00


Reduction-of-unit-multipliers/445898: Anuranjita is driving at a speed of 74 miles per hour. At this speed, how many inches will Anuranjita travel in 1 second?
1 solutions

Answer 307052 by mananth(12270) About Me  on 2011-05-06 04:51:08 (Show Source):
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Anuranjita 74 mph
convert miles to inches and hours to seconds
1760 yards = 1 mile
3feet = 1 yard
12 inches = 1 foot
(1760*3*12*74)/3600
=1302.4 in/sec


Probability-and-statistics/445878: In a recent season, Monique Currie of the Duke Blue Devils scored 635 points. She made a total of 356 shots, including 3 point field goals, 2-point field goals, and 1-point free throws. She made 76 more 2-point field goals than free throws and 77 more free throws than 3-point field goals. Find the number of each type of shot she made.
Appreciate if someone can help.

1 solutions

Answer 307051 by mananth(12270) About Me  on 2011-05-06 04:45:09 (Show Source):
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Free throw goals =x
2pt field goals = x+76
3pt field goals=x-77
x+x+76+x-77=356
3x-1=356
3x=357
x=119 free throw goals
x+76 = 2 pt field goals = 119 +76=195
x-77 = 119-77 = 42 -- 3pt goals
CHECK
119*1 + 2*195+3*42= 635 points


Linear_Equations_And_Systems_Word_Problems/445894: a) John is now 3 times as old as his brother Sam. In 5 years, John will be twice as old as Sam will be then. Find their present ages.
1 solutions

Answer 307048 by mananth(12270) About Me  on 2011-05-06 04:24:14 (Show Source):
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Sam's age x
John's age 3x
5 years later
Sam's age x+5
John's age 3x+5
John's age 2 times older
3x+5=2(x+5)
3x+5=2x+10
x=10-5
x=5
x= 5 Sam's age
3x=15 John's age


Geometric_formulas/445889: If there were 600 people at a play, the total receipts were 9,800 pesos, and the admission price was 20 pesos for adults and 10 pesos for children, how many adults and how many children were in attendance? .....thank you
1 solutions

Answer 307047 by mananth(12270) About Me  on 2011-05-06 04:17:36 (Show Source):
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Adult x Numbers
Child ------------ y Numbers
x+y=600 .............1
20x+10y=9800 .............2
Eliminate y
multiply (1)by -10
Multiply (2) by 1
-10x-10y=-6000
20x+10y=9800
Add the two equations
10x= 3800
/10
x=380
plug value of x in (1)
x+y=600
380+y=600
y=600 -380
y=220


Linear_Equations_And_Systems_Word_Problems/445895: 7 audio cassettes and 3 video cassettes cost rs 1110,while 5 audio cassettes and 4 video cassettes cost rs 1350 find the cost of an audio cassette and a video casette
1 solutions

Answer 307046 by mananth(12270) About Me  on 2011-05-06 04:08:32 (Show Source):
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Video--- x Cost
Audio=== y Cost
3x+7y=1100 .............1
4x+5y=1350 .............2
Eliminate y
multiply (1)by -5
Multiply (2) by 7
-15x-35y=-5500
28x+35y =9450
Add the two equations
13x=3950
/13
x= Rs.303.85 Cost of Video
plug value of x in (1)
3x+7y=1100
911.54 +7y=1100
7 y = 1100 -911.54
7 y = 188.46
y =Rs.26.92 Audio


Linear_Algebra/445381: What are the solutions to
6x+3y+z=19
x-3y+2z=21
17x-2y+3z=86
1 solutions

Answer 306806 by mananth(12270) About Me  on 2011-05-05 06:47:14 (Show Source):
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6x+3y+z =19--------------1
x-3y+2z=21--------------2
17x-2y+ 2z=86-----------3

consider equation 1 &2 Eliminate y
Add the two
7x+3z=40-------------4
consider equation 2 & 3 Eliminate y
7x+3z=40--------------5
Multiply 2 by -2
Multiply 3 by 3
we get
-2x+6y-4z=-42
51x-6y+ 6z=258
Add the two
49x+2z=216 -------------5 5
Consider (4) & (5) Eliminate z
Multiply 4 by -7
Multiply (5) by 1
we get
-49x-21z=-280
49x+2z=216
Add the two
-19z=-64
/-19
z=3.37
Plug the value of z in 5
49x+6.74=216
49x=209.26
x=4.27
plug value of x & z in 1
25.62+3y+3.37=19
3y=-25.62-3.37+ 19
y=-9.99

m.ananth@hotmail.ca


Quadratic_Equations/445401: A rectangular garden with dimensions 18yd by 24yd is to have a sidewalk of uniform width placed completely around the inside of its border in such a way that the area of the remaining garden is 216 yd. how wide is the sidewalk?
1 solutions

Answer 306804 by mananth(12270) About Me  on 2011-05-05 06:30:27 (Show Source):
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Let the width of sidewalk be x
..
Length of ground =24
Width = 18

Area = 432 M^2
Area of sidewalk = 68M^2
(24-2x)(18-2x)=216
432-48x-36x+4X^2=216
4X^2-84x-216=0
/4
x^2-21x-54=0
(x-18)(x-3)=-
x=18 OR x=3
the with is obviously 3 yards


Triangles/445399: a garden has the shape of a right triangle with one leg 5 meters longer than the other. the hypotenuse is 5 meters less than twice the length of the shorter leg
what is the length of the shorter leg?
1 solutions

Answer 306800 by mananth(12270) About Me  on 2011-05-05 06:10:13 (Show Source):
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shorter leg =x
longer leg = x+5
hyp=2x-5
...
Apply Pythagoras theorem
x^2+(x+5)^2=(2x-5)^2
x^2+x^2+10x+25=4x^2-20x+25
group the terms
2x^2-30x=0
2x(x-15)=0
so x= 15
..
15^2+20 ^2= 625
(2x-5)^2= 625


Age_Word_Problems/445406: A father is 3 times older than his son now. In 10 years time their combined ages will b 68. How old are they now?
1 solutions

Answer 306798 by mananth(12270) About Me  on 2011-05-05 06:01:52 (Show Source):
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son =x
father = 3x
..
after 10 years
son = x+10
father= 3x+10
...
x+10+3x+10= 68
4x+20=68
4x=48
x=12 yera son's age
father = 36 years


Age_Word_Problems/445412: Mary is twice as old as John and half as old as Bob.in 22 years time, Bob will be twice as old as John. how old is Mary?
1 solutions

Answer 306796 by mananth(12270) About Me  on 2011-05-05 05:59:32 (Show Source):
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Mary =x
John= x/2 (because mary is twice Bob's age)
Bob = 2x ( mary is 1/2 John's age)
After 22 years
Bob = 2x+22
John = x/2 + 22
2x+22= 2(x/2+22)
2x+22=x+44
2x-x=44-22
x=22 Mary's age


Geometry_Word_Problems/445368: A ladder 26 ft long is placed 10 ft from the base of a house. How high up the side of the house does the ladder reach?
1 solutions

Answer 306791 by mananth(12270) About Me  on 2011-05-04 23:47:00 (Show Source):
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let the height be x
using pythagoras theorem
x^2+10^2=26^2
x^2+100=676
x^2=576
x= sqrt576
x=24 feet the height


Radicals/445296: The time (sec) it takes for an object to fall from a height of h(ft) is expressed by the following equation:
H = 16t^2. Solve the equation for t.

1 solutions

Answer 306790 by mananth(12270) About Me  on 2011-05-04 22:23:37 (Show Source):


Polynomials-and-rational-expressions/445311: I need help answering this math problem.
81x^2 over 5x^2-10x+5* 5x-5 over 9x can you help me and explain how to get to the answer thank you
1 solutions

Answer 306789 by mananth(12270) About Me  on 2011-05-04 22:21:30 (Show Source):
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81x^2 over 5x^2-10x+5* 5x-5 over 9x
%2881x%5E2%2F%285x%5E2-10x%2B5%29%29%2A%28%28+5x-5%29%2F%289x%29%29

%289x%2A9x%2F%285%28x%5E2-2x%2B1%29%29%29%2A%28%28+5%28x-1%29%29%2F%289x%29%29
%289x%2A9x%2F%285%28x-1%29%5E2%29%29%2A%28%28+5%28x-1%29%29%2F%289x%29%29
9x%2F%28x-1%29


Surface-area/445280: what is the surface area of 3 ft by 3 ft by 4 ft/
1 solutions

Answer 306780 by mananth(12270) About Me  on 2011-05-04 21:49:19 (Show Source):
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2(3*3)+2(3*4)+2(2*3)
18+24+12=54 sq.ft


Evaluation_Word_Problems/445292: factor completely
m^4-n^4
1 solutions

Answer 306778 by mananth(12270) About Me  on 2011-05-04 21:47:05 (Show Source):


Money_Word_Problems/445229: Here's my problem: I don't know how to write an algebraic equation to work this out. Please help, thank you very much.
John bought two computers. One desktop and one laptop. Before finance charges, the laptop cost $1000 more than the desktop. John paid for the computers using two different financing plans. For the desktop, the interest rate was 8.5% per year, and the laptop was 7.5% per year. The total finance charges for one year were $915. How much did the desktop computer cost before finance charges?
1 solutions

Answer 306762 by mananth(12270) About Me  on 2011-05-04 20:38:26 (Show Source):
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Laptop x Cost
Desktop ----------y Cost
x-y=1000 .............1
0.075x+0.085y=915 .............2
Eliminate y
multiply (1)by 0.085
Multiply (2) by 1
0.085 x -0.085 y = 85
0.075 x +0.085y = 915
Add the two equations
0.16 x= 1000
/ 0.16
x = 6,250.00
plug value of x in (1)
x-y=1000
6250-y= 1000
-y=1000 -6250
-y=-5250
y=5250.00