Posted by **m** on Monday, February 21, 2011 at 7:57pm.

addition method:3x-5y=-2 and 5y-2x=-2

how would I solve it since they are not together?

- algebra -
**MathMate**, Monday, February 21, 2011 at 10:52pm
These simultaneous equations can be solved most of the time by either substitution or by elimination. We will try elimination here, since I see 5y in both equations.

3x-5y=-2....(1)

5y-2x=-2....(2)

Rearrange to line up x and y in columns

3x-5y=-2...(1a)

-2x+5y=-2...(2a)

Add the two equations:

3x-2x -5y+5y = -2 -2

simplify to get

x = -4 ... (3)

Substitute (3) into (1) to get

3(-4)-5y=-2

-5y = -2 + 12

-5y = 10

y = 10 / (-5) = -2 ..(4)

(3) and (4) give the final answer, but we still have one more step to do: check!

Substitute (3) and (4) into (1) and (2) to get

3(-4)-5(-2)

=-12+10

=-2 from (1) OK

5(-2)-2(-4)

=-10+8

=-2 from (2) OK

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