Posted by **Sam** on Saturday, April 6, 2013 at 6:39pm.

I cannot solve these last three systems. Could you show me the work for them so i understand how to do them.

1)

x-y=1

2x+y=5

3x-4y=2

2)

5x+8y+6z=14

2x+5y+z=12

-3x+6y-12z=20

3)

x^2+2xy-2y^2=-11

x^2+xy-2y^2=-9

- Math Systems -
**Ollie**, Saturday, April 6, 2013 at 6:49pm
problem 1

in the equation x - y = 1, solve for x in terms of y.

replace x in either of the other two equations and you will be able to solve for x. Now, you can go back to any of the three equations and replace x with the value you found and solve for y.

Check that your solution for x and y satisfy all three equations.

- Math Systems - Partial answer -
**Ms. Sue**, Saturday, April 6, 2013 at 6:51pm
1)

x-y=1

x = 1 + y

2x+y=5

2(1 + y) + y = 5

2 + 2y + y = 5

3y = 3

y = 1

3x-4y=2

3x - 4 = 2

3x = 6

x = 2

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