2y+8x=10...........Eq,1.And 4y+x=20........Eq,2.Find x?.?

italien bum2012-03-23T01:55:42Z

Favorite Answer

there are two methods

Method one:
isolate one variable and plug it's value into the second equation

2y+8x=10
2y=10-8x
y=5-4x
plug into 4y+x=20
4(5-4x)+x=20
20-16x+x=20
20-15x=20
0=15x
x=0

Method two:
add or subtract the equations so that one variable cancels out
2y+8x=10 multiplied by 2 is 4y+16x=20
subtract the second equation 4y+x=20 from this equation
4y+16x=20
-(4y+x=20)

4y+16x=20
-4y-x=-20
--------------
15x=0

x=0



you could also isolate y in both equations and set the expressions for y equal to eachother:
2y+8x=10
2y=10-8x
y=5-4x

4y+x=20
4y=20-x
y=(20-x)/4

y=y
5-4x=(20-x)/4
20-16x=20-x
20=20+15x
0=15x
x=0

DOVE2012-03-23T09:20:18Z

2y+8x=10...........Eq,1.
4y+x=20.............Eq,2
Multiply Eq1 with 2
4y+16x=20
subtract from Eq2
x-16x= 20- 20=0
-15x=0
x=0
From Eq2
4y+x=20
4y+0=20
y=5

Lesego Napo2012-03-23T09:01:00Z

in eq 1 put y subject of the formula : y=(10-8x)/(2)

substitude y of eq 1 in eq 2 : 4((10-8x)/(2)))+x=20

40-16x+x=20
-15x=-20
x=20/15 thats the answer.

?2012-03-23T09:00:33Z

8x+2y=10 ----(1)x2
x+4y=20 -------(2)

16x+4y=20 ----(3)
x+4y=20 ------(4)
- - -
----------------
15x = 0
x=0