SOLUTION: This is my last question that I need an answer for. I tried many times but the answer was wrong. 3x + 2y =8 -x + y = 9 I have to solve using substitution, and can you also tell

Algebra ->  Linear-equations -> SOLUTION: This is my last question that I need an answer for. I tried many times but the answer was wrong. 3x + 2y =8 -x + y = 9 I have to solve using substitution, and can you also tell      Log On


   

Question 1036662: This is my last question that I need an answer for. I tried many times but the answer was wrong.
3x + 2y =8
-x + y = 9
I have to solve using substitution, and can you also tell me why you did what you did
example:
"In order to get this, you must first multiply by 2"
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
(1) +3x+%2B+2y+=+8+
(2) +-x+%2B+y+=+9+
--------------------
Add +x+ to both sides of (2)
(2) +y+=+9+%2B+x+
Substitute this result into (1)
(1) +3x+%2B+2%2A%28+9+%2B+x+%29+=+8+
(1) +3x+%2B+18+%2B+2x+=+8+
(1) +5x+%2B+18+=+8+
(1) +5x+=+-10+
(1) +x+=+-2+
---------------
Substitute this result into (2)
(2) +-x+%2B+y+=+9+
(2) +-%28-2%29+%2B+y+=+9+
(2) +2+%2B+y+=+9+
(2) +y+=+7+
----------------
check answers:
(1) +3x+%2B+2y+=+8+
(1) +3%2A%28-2%29+%2B+2%2A7+=+8+
(1) +-6+%2B+14+=+8+
(1) +8+=+8+
OK
(2) +-x+%2B+y+=+9+
(2) +-%28-2%29+%2B+7+=+9+
(2) +2+%2B+7+=+9+
(2) +9+=+9+
OK