SOLUTION: Solve using the multiplication principle first. Then add. Then show your check for both equations. -x-y=8 equation (1) 2x-y=-1 equation (2) I think I have the correct answ

Algebra.Com
Question 412030: Solve using the multiplication principle first. Then add. Then show your check for both equations.
-x-y=8 equation (1)
2x-y=-1 equation (2)
I think I have the correct answers. x=-3 and y=-5. My problem is my check on the first equation -x-y=8. I cannot get it to check. The second equation checks. 2x-y=-1: 2*3-(-5)=-1. Can you show me how to check -x-y=8 please. I have spent an hour trying to get this to check and it won't. This algebra area we are doing is System of equations the elimination method and we have to do the multiplication principle first, then add, then do our checks for each equation. I have to turn this in first thing in the morning and I am frustrated at this point because I cannot make the first problem check. Please help.
Found 2 solutions by solver91311, ewatrrr:
Answer by solver91311(24713)   (Show Source): You can put this solution on YOUR website!


You say the solution set is the ordered pair (-3,-5), so:







Looks like it checks to me.

John

My calculator said it, I believe it, that settles it
The Out Campaign: Scarlet Letter of Atheism
Answer by ewatrrr(24785)   (Show Source): You can put this solution on YOUR website!


Hi

Solve using the multiplication principle first.  Then add.

-x-y=8 equation (1)

2x-y=-1 equation (2) 



-2x-2y=16 |multiplying 1st Eq thru by 2 and then adding to eliminate x

 2x-y =-1 

  -3y = 15

    y = -5  and 

2x = y-1 = -6;

    x = -3



CHECKING our Answer***

 3 + 5 = 8   |this checks...  -(-3) -(-5) = 3 + 5 = 8

 -6+5 = -1



 

RELATED QUESTIONS


solve using the Multiplication principle first then add
X=3Y,... (answered by checkley75)

please post your steps used to solve the following question:	Solve using the... (answered by josmiceli)

Solve using the multiplication principle first. Then use the elimination method.
2x+y=13
 (answered by sophxmai)

Solve using the multiplication principle first. Then use the elimination method.
2x+y=13  (answered by mananth)

Solve using the multiplication principle first. Then use the elimination method.
2x+y=13
 (answered by user_dude2008)

Solve using the multiplication principle first. Then use the elimination method.
2x+y=13
 (answered by stanbon,mananth)

Using both the addition principle and multiplication principle, solve: 
x + 1/4... (answered by ikleyn,josgarithmetic)

I am a math tutor on this site, can someone please help with a method of systems of... (answered by stanbon)

Please help solve this problem.I come up with x= 4 and y= -1...Not too sure what to do... (answered by josmiceli)