# 7th grade math check

posted by saranghae12

Ok I was wondering if you could check these 3 problems please. I am suppose to set these equations equal but I am not sure if did them right. I think I accidently solved these systems as substitutions. The answers are suppose to be in coordinate pairs.

1) x - y = 11
-3x + y = -21
I got (5,-16)

2) 5x - 4y = 17
-10x + 4y = -42
I got (5,3)

3) x + 3y = -1
3x + 3y = 15
I got (4,1)

Please check if i did it correctly please. thank you

1. MathGuru

Check your solutions with both equations. If your solutions don't fit both, then your answers need to be reworked. For example, using the solution you have for 1):

x = 5
y = -16

5 - (-16) = 11 -->false
-3(5) - 16 = -21 -->false

Solution for this system should be (5,-6).

5 - (-6) = 11 -->true
-3(5) - 6 = -21 -->true

Try the others again.

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