SOLUTION: 2x-y=3 x+y=12

Algebra ->  Sequences-and-series -> SOLUTION: 2x-y=3 x+y=12       Log On


   



Question 1131461: 2x-y=3
x+y=12

Found 2 solutions by rothauserc, josmiceli:
Answer by rothauserc(4718) About Me  (Show Source):
You can put this solution on YOUR website!
1) 2x -y = 3
:
2) x+ y = 12
:
add equations 1 and 2 together
:
3x = 15
:
x = 5
:
substitute for x in equation 2
:
5 +y = 12
:
y = 7
:
*************************************************
x = 5, y = 7
:
check answers
:
equation 1
:
2x -y = 3
:
2(5) -7 = 3
:
10 -7 = 3
:
3 = 3
:
equation 2
:
x+ y = 12
:
5 +7 = 12
:
12 = 12
:
answer checks
*****************************
:

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
+2x+-+y+=+3+
+x+%2B+y+=+12+
---------------------
Add the equations
+3x+=+15+
+x+=+5+
Put this result back into either of the equations
+x+%2B+y+=+12+
+5+%2B+y+=+12+
Subtract +5+ from both sides
+y+=+12+-+5+
+y+=+7+
-----------------------
The solution is ( 5, 7 )
-----------------------------
check:
+2x+-+y+=+3+
+2%2A5+-+7+=+3+
+10+-+7+=+3+
+3+=+3+
OK