Solve the system of equations; If you can not find a solution, label the lines as parallel or coinciding?

Explain why.
1) x+y=5
y=7-x

2) 3x-y=2
16x-5y=11

3) 3over5x – 7over5y = 1
x-7over5y=5over3

4) y=3x-9
2x-y=6

5) x=3y
2x-5y=0
any help would be greatly appreciated Please NO smart comments Thank You!

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2 Comments for Solve the system of equations; If you can not find a solution, label the lines as parallel or coinciding?

1. Rita the dog | February 15th, 2011 at 8:59 am

1) First equation y = -x + 5, second equation y = -x + 7. Both have slope -1, so they are parallel and do not cross. Conclusion: the system has no solution.
2. AbeLincolnParty | February 15th, 2011 at 9:35 am

If after manipulation, the equations are exact multiples of one another then they coincide. All equations that coincide are also parallel.

If the equations have the same slope, but are not exact multiples of one another, then they are parallel.