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Linear-equations/580486: solve this equation using the elimination method:
y=-18/19x-416/19
y= -17/19x-414/19
1 solutions

Answer 371263 by mananth(12270) About Me  on 2012-02-29 22:10:06 (Show Source):
You can put this solution on YOUR website!
y=-18/19x-416/19
y= -17/19x-414/19
equate the two equations
%28-18%2F19%29x-%28416%2F19%29+=+%28-17%2F19%29x-%28414%2F19%29

%28-18%2F19%29x-%28-17%2F19%29x=%28416%2F19%29-%28414%2F19%29

%28-18%2F19%29x%2B%2817%2F19%29x=%28416%2F19%29-%28414%2F19%29

%28-1%2F19%29x=+2%2F19
-x=2
x=+-2







Mixture_Word_Problems/580475: How much of a pure 100% acid must be added to 2 liters of a 10% acid solution in order to produce a 20% solution? How much 20% solution will there be?
1 solutions

Answer 371256 by mananth(12270) About Me  on 2012-02-29 21:59:29 (Show Source):
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------------ percent ---------------- Amount
Acid type I 10 ---------------- 2 liters
Pure acid 100 ---------------- x liters
Total 20 ---------------- 2 + x liters

10*2+100x=20(2 +x)
20+100 x=40+20 x
100x-20 x =-20+ 40
80 x = 20
/ 80
x = 0.25 of liters Pure acid
0.25 of liters Acid type I
m.ananth@hotmail.ca


Linear-equations/580378: write an equation of a vertical line through (4,3).
write an equation of the line parallel to the line 8x - 2y = 7 passing through (2,-1).
find all values of x for which (x,6) is on the graph of f (x) = x2 + 3x -4
1 solutions

Answer 371227 by mananth(12270) About Me  on 2012-02-29 20:24:55 (Show Source):
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write an equation of a vertical line through (4,3).
x=4
write an equation of the line parallel to the line 8x - 2y = 7 passing through (2,-1).
8 x -2 y = 7
Find the slope of this line
make y the subject
-2 y = -8 x + 7
Divide by -2
y = 4 x -3 1/2
Compare this equation with y=mx+b
slope m = 4
The slope of a line parallel to the above line will be the same
The slope of the required line will be 4
m= 4 ,point ( 2 , -1 )
Find b by plugging the values of m & the point in
y=mx+b
-1 = 8 + b
b= 9
m= 4
Plug value of the slope and b in y = mx +b
The required equation isy = 4 x + 9



find all values of x for which (x,6) is on the graph of f (x) = x2 + 3x -4
6=x^2+3x-5
x^2+3x-10=0
(x+5)(x-2)=0
x=-5 & 2


Linear-systems/580387: 5y=7x+22
x=-6y+17
1 solutions

Answer 371225 by mananth(12270) About Me  on 2012-02-29 20:18:53 (Show Source):
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5y=7x+22
x=-6y+17
Re write the equations


-7 x + 5 y = 22 .............1
1 x + 6 y = 17 .............2
Eliminate y
multiply (1)by -6
Multiply (2) by 5
42 x -30 y = -132
5 x + 30 y = 85
Add the two equations
47 x = -47
/ 47
x = -1
plug value of x in (1)
-7 x + 5 y = 22
7 + 5 y = 22
5 y = 22 -7
5 y = 15
y = 3


Numbers_Word_Problems/580381: The sum of the digits in a two-digit number is 7. The new number obtained when the digits are reversed is 27 less than the original number. Find the original number
1 solutions

Answer 371221 by mananth(12270) About Me  on 2012-02-29 20:12:47 (Show Source):
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let the two digit number be xy
x in the ten's place & y in units place
x+y=7........................(1)
10y+x= 10x+y-27
9y-9x=27
/9
y-x=3........................(2)
Add (1) & (2)
2y= 7+3
2y=10
y=5
x+y =7
y=5
so x= 2
The number is 25


percentage/580373: William has scored a total of 235 points on the first three math tests taken in his mathematics class. If his mathematics tests are always worth 100 points, how many points must he earn on his next test in order to have an average of 80%?


a.) 80
b.) 85
c.) 90
d.) 95
Thank you in advance! Btw, if you can, could you please also show step by step examples on how to solve and do slopes on charts?
1 solutions

Answer 371217 by mananth(12270) About Me  on 2012-02-29 20:02:33 (Show Source):
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assume he has to get x points to get an average of 80

His total points will be 235+x
Number of tests will be 4
(235+x)/4 = 80
multiply by 4
235+x= 4*80
235+x= 320
x=320-235
x= 85
he has to get 85 points to average 80


Linear-systems/580339: I need help with solving 3x+y=-8 and -2x-y=6 by substitution.
1 solutions

Answer 371210 by mananth(12270) About Me  on 2012-02-29 19:26:27 (Show Source):
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3x+1y= -8 .............1
y=-8-3x

-2x-y= 6
Substitute y in (2)
-2x-1(-8-3x)=6
-2x+8+3x=6
-2x+3x= -2
x=-2
/ 1
x=-2
Plug the value of x in (1)
3x+y=-8
3*-2+y =-8
-6 + y = -8
1 y = -2
/ 1
y= -2
m.ananth@hotmail.ca


Linear-systems/580321: An airplane flew for 6 hours with a 22-km/h tail wind. the return flight against the same wind took 8 hours. find the speed of the plane in stil air. how do i set up this equation?
1 solutions

Answer 371207 by mananth(12270) About Me  on 2012-02-29 19:20:11 (Show Source):
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let the distance be y
speed of plane in still air be x
withwind speed = x+22
against wind speed = x-22
time with wind = 6 hours
time against wind = 8 hours
distance = speed & time
(x+22)6 =Y
(x-22)*8 y
(x+22)*6 = (x-22)*8
6x+132=8x-176
8x-6x=132+176
2x=308
/2
x= 154
Speed of plane in still air = 154 mph


test/580326: y= -3x
y= x-8
Solving linear equations using the substitution method
1 solutions

Answer 371202 by mananth(12270) About Me  on 2012-02-29 19:09:01 (Show Source):
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y= -3x
y= x-8
substitute y in the second equation
-3x=x-8
add -x to both sides
-4x=-8
/-4
x=2
plug x =2 in y=-3x
y=-3*2
y=-6


Surface-area/579969: What is an equation for the surface area of a cylinder whose height is equal to its diameter as a function on its volume? HELP!
1 solutions

Answer 371112 by mananth(12270) About Me  on 2012-02-29 09:49:04 (Show Source):
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Volume V = pi * r^2 * h
h=2r
V= pi * r^2*(2r)^2
V= pi*4r^4


Linear-equations/579968: What is an equation of a line perpendicular to y=2x-7?
1 solutions

Answer 371111 by mananth(12270) About Me  on 2012-02-29 09:46:13 (Show Source):
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A perpendicular to this line can pass through this line at any point.
unless we know the co-ordinates of that point we cannot find the equation
in general
the perpendicular will be y = -1/2 x + something
because the slope is negative reciprocal of the given line


Linear_Equations_And_Systems_Word_Problems/579946: Tim and Judy mix two kinds of feed for pedigreed dogs. They wish to make 35 pounds of feed worth $0.36 per pound by mixing one kind worth $0.18 per pound with another worth $0.53 per pound. How many pounds of the cheaper kind should they use in the mix?

1 solutions

Answer 371110 by mananth(12270) About Me  on 2012-02-29 09:37:26 (Show Source):
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$ ---------------- quantity
Type I 0.18 ---------------- x pounds
Type II 0.53 ------ 35 - x pounds
Mixture 0.36 ---------------- 35

0.18x+0.53(35-x)=0.36*35
0.18x+0.53(35-x )=12.6
0.18x+ 18.55-0.53x=12.6
0.18x-0.53x=12.6--18.55
-0.35 x = -5.95
/ -0.35
x=17 pounds$ 0.18 Type I
18 pounds$ 0.53 Type II

m.ananth@hotmail.ca


Linear-systems/579932: When using the addition method, I don't understand how to solve this problem:
4x+5/2y=11
3x-4/3y= -11
I did what my textbook suggested and tried to eliminate fractions, but ended up with something even more difficult:
24x+15y=11
18x-8y= -11
Please help I'm not sure what I should do!
Christina
1 solutions

Answer 371103 by mananth(12270) About Me  on 2012-02-29 09:00:30 (Show Source):
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(4x+5)/2y=11
multipluy by 2y
4x+5 = 22y
4x-22y=-5.....................(1)
(3x-4)/3y= -11
multiply by 3y
3x-4 = -33y
3x+33y=4.......................(2)
4 x -22 y = -5 .............1
3 x + 33 y = 4 .............2
Eliminate y
multiply (1)by 3
Multiply (2) by 2
12 x -66 y = -15
6 x + 66 y = 8
Add the two equations
18 x = -7
/ 18
x = - 7/18
plug value of x in (1)
4 x -22 y = -5
-14/9 -22 y = -5
-22 y = -5 -14/ 9
-22 y = -59/ 9
y = 14/47


Linear_Algebra/579949: what is the slope of (7,0) and (0,-5)
1 solutions

Answer 371101 by mananth(12270) About Me  on 2012-02-29 08:41:36 (Show Source):
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x1 y1 x2 y2
7 0 0 -5

slope m = (y2-y1)/(x2-x1)
( 7 - 0 )/( 0 - -5 )
( -5 / -7 )
m= 5/7



Linear-systems/579893: y-x=3x
2(x+y)=14-y

3a+6b=-15
a=-2b-5
pls. solve by substitution
1 solutions

Answer 371091 by mananth(12270) About Me  on 2012-02-29 01:39:20 (Show Source):
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y-x=3x
add x to both sides
y= 4x

2(x+y)=14-y
substitute y
2(x+4x)=14+3x
10x=14+3x
add -3x to both sides
7x=14
/7
x=2
when x =2 y = 4x = 4*2=8
(2,8)


Triangles/579900: assume x is an acute angle in a right triangle
sin x= 3/4; cos x
how do i solve this?

1 solutions

Answer 371090 by mananth(12270) About Me  on 2012-02-29 01:35:35 (Show Source):
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Sin x = 3/4
sin x = opposite side / hypotenuse=3/4
opposite side = 3
hypotenuse = 4
so adjacent side = sqrt(4^2-3^2) by hypotenuse theorem
sqrt%2816-9%29
=sqrt%287%29
Cos x = adjacent side / hypotenuse
Cos x = sqrt%287%29%2F4


Geometry_Word_Problems/579894: 1. From a second - story window directly across the street, the angle of elevation of the top of an office building is 57 degrees and 20 minutes and the angle of depression of the base is 18 degrees and 10 minutes. If the buildings are 38 m. apart, what is the height of the building ?
2. Mr. Reyes wanted to know the height of the tree. What he did was form a point A on the ground and observed that the angle of elevation of the top of the tree was 30 degrees. He then moved 50 ft. away from A. In his second position at B, the angle of elevation of the top of the tree was 22 degrees. Find the height of the tree.
1 solutions

Answer 371087 by mananth(12270) About Me  on 2012-02-29 01:30:32 (Show Source):
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angle of elevation = 57 deg 27 mins
distance from the window = 38 m
let the height of office be h
Let the vertical heightbetween the window and the office be x feet.
height of office upto level of window=
Tan 57 27' = x/38
angle of depression is 18 10'
vertical height of window from the ground = (h-x)
Tan 18 10' = (h-x)/38
Tan 57 27'+Tan 18 10' = (h-x)/38 + x/38
Tan 57 27'+Tan 18 10'= h/38 -x/38 +x/38
Tan 57 27'+Tan 18 10' = h/38
Tan 57.45 + Tan 18.17 = h/38
1.57 + 0.33 = h/38
1.9= h/38
h= 1.9 *38
h= 72.2 m
----------------
From point A angle of elevation = 30 deg
From point B angle of elevation = 22 deg
distance AB = 50 ft.
let height of tree be h
and distance from point A be x
Tan 30 = h/x
Cot 30 = x/h
Point B
Tan 22 = h/(50+x)
cot 22 = (50+x)/h
Cot 22- Cot 30 = 50/h +x/h - x/h
2.475-1.733= 50/h
0.742= 50/h
h= 50/0.742
67.38 feet












Numbers_Word_Problems/579854: I need help with the following problem:
Three times the smallest of 3 consecutive even integers plus the sum of the other 2 is 66. Find the numbers.

1 solutions

Answer 371081 by mananth(12270) About Me  on 2012-02-28 22:41:34 (Show Source):
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let the consequtive even numbers be
x, x+2, x+4
3x+(x+2)+(x+4)=66
3x+x+2+x+4=66
5x+6=66
add -6 to both sides
5x=60
x=60/5
x= 12
The numbers are 12,14,16


Triangles/579844: What is the value of x if the triangle is 15 square yards?
Base of the triangle is x-5
Height of the triangle is 2x + 1
1 solutions

Answer 371080 by mananth(12270) About Me  on 2012-02-28 22:38:20 (Show Source):
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Area of triangle = 1/2 * base * height
15= 1/2 * (x-5)(2x+1)
multiply by 2
30 = (x-5)(2x+1)
30= x(2x+1)-5(2x+1)
30=2x^2+x-10x-5
30=2x^2-9x-5
add -30
0= 2x^2-9x-35
2x^2-9x-35=0
2x^2-14x+5x-35=0
2x(x-7)+5(x-7)=0
(x-7)(x+5)=0
x=7 OR -5
x=7 since the lengths cannot be negative.


Geometry_Word_Problems/579849: If each side of a square is increased by 3 cm, the total area of both the new square and the original square will be 617 cm2 . Approximate to the nearest tenth of a centimeter the length of each side of the original square.
1 solutions

Answer 371077 by mananth(12270) About Me  on 2012-02-28 22:29:19 (Show Source):
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let side of square be x
area = l*w= x^2
3 is added to its side
Area of this square = (x+3)^2
x^2+(x+3)^2= 617
x^2+x^2+6x+9=617
2x^2+6x-617+9=0
2x^2+6x-608=0
/2
x^2+3x-304 =0
x^2+19x-16x-304=0
x(x+19)-16(x+19)=0
(x+19)(x-16)=0
x=-19 OR 16
ignore negative
the length of side = 16cm


Linear_Equations_And_Systems_Word_Problems/579833: if henry has 45 nickels and dimes totaling $2.90, write an equation that can be used as part of a system of equations to determine how many nickels (n) and dimes (d) henry has.
1 solutions

Answer 371074 by mananth(12270) About Me  on 2012-02-28 22:24:53 (Show Source):
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let x be the nickels
y the dimes
x+y=45
0.05x+0.1y = 2.90
solve to get x & y


Functions/579738: Hello. I need help with these questions please. I need asap. Thank you. If you can, please explain how you got the answer. Thanks
1. Find the slope and the y-intercept of the line. Write fractional answers in lowest terms.
4y+7x+9= 14+7x
The slope is:
The y-intercept is (0, )
2. Find the slope if it exists of the line containing the pair of points.

(-10.3, 11.8) and (-9.9,4.3)
The slope is:

3. Find the slope and the y-intercept.

f(x)= -9x-7
The slope is:
The y-intercept is (0, )

4. Find an equation of the line having the given slope and containing the given point. Express your answer in the form x=a, y=b, or y=mx+b
m = -4,(9,0)
The equation of the line is y=

5. Write an equation of the line containing the given point and parallel to the given line. Express your answer in the form y=mx+b

(-4,9);9x=4y+7
The equation of the line is y=



1 solutions

Answer 371050 by mananth(12270) About Me  on 2012-02-28 20:14:14 (Show Source):
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1. Find the slope and the y-intercept of the line. Write fractional answers in lowest terms.
4y+7x+9= 14+7x
4y=5
y=5/4
The slope is:
The y-intercept is (0, 5/4)
2. Find the slope if it exists of the line containing the pair of points.

(-10.3, 11.8) and (-9.9,4.3)
The slope is:-18.75

3. Find the slope and the y-intercept.

f(x)= -9x-7
The slope is:-9
The y-intercept is (0, -7 )

4. Find an equation of the line having the given slope and containing the given point. Express your answer in the form x=a, y=b, or y=mx+b
m = -4,(9,0)
The equation of the line is y=-4x+36

5. Write an equation of the line containing the given point and parallel to the given line. Express your answer in the form y=mx+b

(-4,9);9x=4y+7
The equation of the line is y=(9/4)x-47/4
Hope this helps you in your online homework




Rectangles/579704: I have a problem on my homework that I cannot figure out. The question is "If P=2L+ 2W, L=11 feet, and P=25 feet, what is W?" I've tried to figure it out, but I forgot how to solve an equation that looks like that. Coul you please help?
1 solutions

Answer 371049 by mananth(12270) About Me  on 2012-02-28 19:55:34 (Show Source):
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p=2l+2w
l=11
p=25
plug l & p in the equation
25= 2*11+2w
25=22+2w
add -22 to both sides
25-22=22-22+2w
3=2w
/2
3/2 = w
w= 1.5 ft.



Problems-with-consecutive-odd-even-integers/579722: what are 2 consecutive even integers whose product plus two is 290
1 solutions

Answer 371048 by mananth(12270) About Me  on 2012-02-28 19:50:58 (Show Source):
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let the integers be x & (x+2)
x(x+2)+2=290
x^2+2x+2=290
Add -2 to both sides
x^2+2x-288=0
x^2+18x-16x-288=0
x(x+18)-16(x+18)=0
(x+18)(x-16)=0
x=-18, x=16
The numbers are 16 & 18
OR
-18, -16


test/579689: One drain pipe can empty a swimming pool in 6 h another pipe takes 3 h if both pipes are used at the same time to drain the pool what part of the job is completed in 2 h? in x h?
1 solutions

Answer 371045 by mananth(12270) About Me  on 2012-02-28 19:45:23 (Show Source):
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Emptying the pool is one job
Faucet I 6 hours
It does 1/ 6 of the job in 1 hour
Faucet II 3 hours
It does 1/ 3 of thejob in 1 hour
Together they will do 1/ 6 + 1/ 3
Together they will do 1/ 2 of the job in one hour
So in 2 hours they will complete emptying the pool


test/579706: What is 49a squared + 16=56a
1 solutions

Answer 371043 by mananth(12270) About Me  on 2012-02-28 19:36:23 (Show Source):
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49a squared + 16=56a
49a%5E2-56a%2B16=0

%287a%29%5E2-%282%29%287a%29%284%29%2B%284%29%5E2=0
this is the identity %28a-b%29%5E2=+a%5E2-2ab%2Bb%5E2
%287a-4%29%5E2


Travel_Word_Problems/579243: With the wind, a plane flew 1780 miles in 6 hours. On the return trip, the pilot was forced to land after 2 hours, having traveled only 440 miles. Find the rate of the plane in still air and the rate of the wind.
1 solutions

Answer 370928 by mananth(12270) About Me  on 2012-02-28 02:18:11 (Show Source):
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Plane speed =x mph
wind speed =y mph
against wind x-y 2 hours
with wind x+y 6 hours

Distance = 1780 miles distance= 440
t=d/r against wind
440.00 / ( x - y )= 2.00

2.00 x - -2.00 y = 440.00 ....................1

1780.00 / ( x + y )= 6.00
6.00 ( x + y ) = 1780.00
6.00 x + 6.00 y = 1780.00 ...............2
Multiply (1) by 3.00
Multiply (2) by 1.00
we get
6.00 x + -6.00 y = 1320.00
6.00 x + 6.00 y = 1780.00
12.00 x = 3100.00
/ 12.00
x = 258.33 mph

plug value of x in (1)
2 x -2 y = 440
516.67 -2 y = 440
-2 y = 440 -516.67
-2 y = -76.67
y = 38.33 mph
Plane speed = 258.33 mph
wind speed = 38.33 mph
m.ananth@hotmail.ca


Geometry_Word_Problems/579237: A lawn is 90 feet long and 40 feet wide. By cutting along the perimeter, how wide is this border if 1/3 of the grass is cut?

More info: provided solution is 5 feet. Student says answer must be derived by using quadratic formula.
X=width of the border
2(90)(x)+2(40)(x)=(90 times 40)/3
Which then does not result in a constant for a to be used in the quadratic formula. B is 260 and c is negative 1200. Since the constant a is zero, i get a divide by zero using the quadratic formula which means to me the answer is infinite but the provided answer is 5. I have made an error but i can't find it. Please advise.
1 solutions

Answer 370910 by mananth(12270) About Me  on 2012-02-27 22:46:41 (Show Source):
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Area of garden = 90 * 40 ft = 3600 sq. ft
1/3 of this area is cut = 1200 sq. ft
Let the uniform width be x
so the reduced length = 90-2x
reduced width = 40-2x
area of this portion is ( 90-2x)((40-2x)
Total area - reduced area = area of the grass cut
3600-(90-2x)(40-2x)= 1200
(90-2x)(40-2x)= 3600-1200
90(40-2x)-2x(40-2x) = 2400
3600-180x-80x+4x^2=2400
4x^2-260x+1200=0
/4
x^2-65x+300=0
x^2-60x-5x+300=0
x(x-60)-5(x-60)=0
(x-60)(x-5)=0
x= 60 not possible
x= 5 ft the width
m.ananth@hotmail.ca




Graphs/579228: y-2=1/3(x+1) what is the y-intercept form and what does is look like on a graph?
1 solutions

Answer 370909 by mananth(12270) About Me  on 2012-02-27 22:33:04 (Show Source):
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y-2=1/3(x+1)
you have to rewrite the equation in the form y = mx+b
where (x,y) are the co-ordinates and m the slope, b the y intercept
multiply by 3
3(y-2) x+1
3y-6 = x+1
3y= x+7
/3
y = (1/3)x+7
This is the equation in slope intercept form

m.ananth@hotmail.ca


Quadratic-relations-and-conic-sections/579216: Find a general form of an equation for the perpendicular bisector of the segment AB.A(8,4)B(-4,14)
1 solutions

Answer 370908 by mananth(12270) About Me  on 2012-02-27 22:24:07 (Show Source):
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.A(8,4)B(-4,14)
First find the midpoint co ordinates (x,y)
x= (x1+x2)/2
y=(y1+y2)/2
x=(8-4)/2 = 2
y= (14+4)/2 = 9
The perpendicular bisector passes through (2,9)
Find the slope of the line, A(8,4)B(-4,14)
x1 y1 x2 y2
8 4 -4 14

slope m = (y2-y1)/(x2-x1)
(14-4)/(-4-8)
( 10 / -12 )
m= - 5/ 6
the line perpendicular to this line will have a slope of (6/5) ( negative reciprocal)
The slope of the perpendicular line is (6/5) and it passes through (2,9)
m= 6/ 5

Plug value of the slope and point( 2 , 9 ) in
y=mx+b
9.00 = 6/5 * 2 +b
b= 9-12/5

b= 33/ 5
So the equation will be
Y = 6/5 x + 33/5

m.ananth@hotmail.ca



Linear-equations/579120: 2X + 6Y = 0
6X - 2Y = 0
I DO NOT UNDERSTAND. I HAVE TO GRAPH THIS EQUATION

1 solutions

Answer 370881 by mananth(12270) About Me  on 2012-02-27 20:31:09 (Show Source):
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2X + 6Y = 0
for x = 3, y=-1 , (3,-1)
for x=6, y=-2(6,-2)
6X - 2Y = 0
for x= 1, y = 3 ( 1,3)
for x=2, y=6 ( 2,6)
Plot the points and find the point of intersection. That is the solution to the system. (0,0)