## Solving this equation by substitution, It my work correct?

Simplificatation, evaluation, linear equations, linear graphs, linear inequalities, basic word problems, etc.
illuminati58
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### Solving this equation by substitution, It my work correct?

x + Y = 6
2x + y =8

2x + y = 8
x + y = 6
x = -y + 6

2 (-y + 6) + y = 8
2y + 12 + y = 8
3y + 12 = 8
3y = - 4
y = -4/3

X = -y + 6
X = -(-4/3) + 6
x = 4/3 + 6
x = 4/3 + 6

{( 12, 4/3 +6 )}
Last edited by illuminati58 on Tue Jul 14, 2009 5:27 pm, edited 1 time in total.

stapel_eliz
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Joined: Mon Dec 08, 2008 4:22 pm
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2 (-y + 6) + 4 = 8
Where did the "4" come from?

illuminati58
Posts: 9
Joined: Sun Jul 12, 2009 11:23 pm
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### Re: Solving this equation by substitution, It my work correct?

Sorry it was a typo but my answer doesnt seem correct
x + Y = 6
2x + y =8

2x + y = 8
x + y = 6
x = -y + 6

2 (-y + 6) + y = 8
2y + 12 + y = 8
3y + 12 = 8
3y = - 4
y = -4/3

X = -y + 6
X = -(-4/3) + 6
x = 4/3 + 6
x = 4/3 + 6

{( 12, 4/3 +6 )}

illuminati58
Posts: 9
Joined: Sun Jul 12, 2009 11:23 pm
Contact:

### Re: Solving this equation by substitution, It my work correct?

x + y = 6
2x + y = 8

x= -y + 6
2(-y+6) + y = 8
- 2y -12 + y = 8
y - 12 = 8
y = 16

x = -y + 6
x = (-16) + 6
x = 16 + 6
x = 22

{(22, 16)}

stapel_eliz
Posts: 1628
Joined: Mon Dec 08, 2008 4:22 pm
Contact:
2 (-y + 6) + y = 8
2y + 12 + y = 8
How did (2)(-y) become 2y?