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Solving equations by using elimination?

0 votes

 

do anyone know ?
x-2y=4
y=x-2

 

1/3x +y=1
-4+y=1

y=x
2y=x+4

-2/7x - 4/3y=8
4/7x+8/3y=-16

asked Mar 14, 2013 in ALGEBRA 1 by Jose Rodriguez Rookie

5 Answers

0 votes

x - 2y = 4

y = x - 2

Add  -y  to each side

-y + y = x -y -2

0 = x - y - 2

Add 2 to each side

2 = x - y

There fore the equations are x - 2y = 4 and x - y = 2

x - 2y = 4     (1)

x - y = 2      (2)

Eliminate x for the above equations then -2y + y = 4-2

-y = 2

y  = -2

Multiply the each side by 2 for the (2) equation

2x - 2y = 4     (3)

Subtract from (1) and (3)

-x + 0 = 0

-x = 0

x = 0

Therefore the values of the equation is x = 0 and y = -2.

answered Mar 14, 2013 by diane Scholar
0 votes

Elimination method.

2) The equations are image and image

The second equation - 4 + = 1

Add 4 to each side .

= 5 _____ (2)

Since the coefficient of the y - term in two equations is same, i can eliminate these terms by sutract equation (2) from first equation.

Write the equations in column form and add to eliminate variable y.

image

The resultant equation is image and solve it for x.

x = - 12

Solution x = -12 and y = 5.

answered Jun 28, 2014 by david Expert
edited Jun 28, 2014 by david
0 votes

Elimination method.

3) The equations are = x  and 2y = x + 4

Write the equations in standard form is ax + by  = c.

- x + y = 0 _____  (1)

- x + 2y = 4 _____ (2)

Step -1

Since the coefficient of the x - term in two equations is same, i can eliminate these terms by sutract second equation  from first equation.

image

The resultant equation is - y = - 4 and solve for y.

Multiply each side by negative one.

y = 4

Step - 2
Subtitute the value in any one of the equations to solve other variable.

Take the equation y = x

Substitute y = 4 we get,

 x = 4

Solution x = 4 and y = 4.

answered Jun 28, 2014 by david Expert
0 votes

Elimination method.

2) The equations are image and image

The second equation - 4 + = 1

Add 4 to each side .

= 5 _____ (2)

Since the coefficient of the y - term in two equations is same, i can eliminate these terms by sutract equation (2) from first equation.

image

The resultant equation is image and solve it for x.

x = - 12

Solution x = -12 and y = 5.

answered Jun 28, 2014 by david Expert
0 votes

4) The equations are

image

image

First equation

image

Multiply each side by negative 2.

image

Observe the two equations are same.

Since they are equal lines there infinitely many solutions.

answered Jun 30, 2014 by david Expert
edited Jun 30, 2014 by david

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