Question

addition method:3x-5y=-2 and 5y-2x=-2
how would I solve it since they are not together?

Answer 1

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