5x=6y+40
2y=8-3x
Solve one equation for one of the variables...
5x = 6y + 40
x = (6/5)y + 8
now, put that into the unused equation...
2y = 8 - 3x
2y = 8 - 3(6/5 y + 8)
2y = 8 - (18/5)y - 24
2y = -(18/5) y - 16
Multiply everything by 5 to get rid of the fraction...
10y = -18y - 80
28y = - 80
y = -80/28 = -20 / 7
Now, put that back into one of the equations to find x.
x = (6/5)y + 8
x = (6/5)(-20/7) + 8
x = (6/1)(-4/7) + 8
x = (-24/7) + 56/7
x = 32/7
So, the answer is (32/7 , -20/7)
2007-05-18 03:30:52
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answer #1
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answered by Mathematica 7
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5x = 6y + 40- - - - - - -Equation 1
2y = 6 - 3x- - - - - - - - Equation 2
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Convert equation 1 and equation 2 to standard form
5x = 6y + 40
5x - 6y - 6y + 40 - 6y
5x - 6y = 40. . . . .Standard form equation 1
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2y = 8 - 3x
3x + 2y = 8 - 3x + 3x
3x + 2y = 8. . . . . . .Standard form equation 2
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5x - 6y = 40
3x + 2y = 8
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Multiply standard form equation 2 by 3
3x + 2y = 8
3(3x + 3(2y) = 3(8)
9x + 6y = 24
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5x - 6y = 40
9x + 6y = 24
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14x = 64
14x / 14 = 64 / 14
x = 64/14
x = 32/7
Insert the x value into equation 2
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2y = 8 - 3x
2y = 8 - 3(32/7)
2y = 8 - 96/7
2y = 56/7 - 96/7
2y = - 40/7
2y / 2 = - 40/7 ÷ 2/1
y = - 40/7 x 1/2
y = - 40 / `14
y = - 20 / 7
Insert the y value into equation 2
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Check equation 2
2x = 8 - 3x
2(- 20/7) = 8 - 3(32/7)
- 40/7 = 8 - 96/7
- 40/7 = 56/7 - 96/7
- 40/7 = - 40/7
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Check equation 1
5x = 6y + 40
5(32/7) = 6(- 20/7) + 40
160/7 = - 120/7 + 280/7
160/7 = 160/7
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Both equations balance
The solution set is { 32/7, - 20/7 }
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2007-05-18 10:53:01
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answer #2
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answered by SAMUEL D 7
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Since 2y=9-3x, then 6y = 24-9x.
Substituting this in first equation gives 5x=24-9x+40 and
14x = 64, thus x= 32/7 then 2y= 8-96/7 and 2y= -40/7 and
y=-20/7
2007-05-18 10:33:07
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answer #3
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answered by ? 3
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5x - 6y = 40
3x + 2y = 8--------X by 3
5x - 6y = 40
9x + 6y = 24-------ADD
14x = 64
x = 64 / 14 = 32 / 7
96/7 + 2y = 8
2y = 56/7 - 96/7
2y = - 40 / 7
y = - 20 / 7
x = 32 / 7 , y = - 20 / 7
2007-05-18 12:15:18
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answer #4
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answered by Como 7
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i got as far as
-5/3x = 3y - 5
It should be taken down further
2007-05-18 10:26:38
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answer #5
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answered by Anonymous
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