SOLUTION: Plz help me with this.. Solve the following systems of equation using addition to eliminate one. If the system has no solution,indicate that it is inconsistent;if it has infininte

Algebra ->  Finance -> SOLUTION: Plz help me with this.. Solve the following systems of equation using addition to eliminate one. If the system has no solution,indicate that it is inconsistent;if it has infininte      Log On


   

Question 949229: Plz help me with this..
Solve the following systems of equation using addition to eliminate one. If the system has no solution,indicate that it is inconsistent;if it has infininte solutions,indicate that it is Dependant;if the system has one solution,check your answer.
-y=2x
3x+y=20.. Thanks
Answer by MathLover1(20849) About Me  (Show Source):
You can put this solution on YOUR website!
-y=2x.....write in standard form
3x%2By=20
-----------------
-2x-y=0...both sides multiply by 3
3x%2By=20...both sides multiply by 2
-----------------
-6x-3y=0
6x%2B2y=40
-----------------...add
-6x-3y%2B6x%2B2y=0%2B40
-3y%2B2y=40
-y=40
y=40%2F-1
y=-40
now find x
-y=2x
-%28-40%29=2x
40=2x
40%2F2=x
x=20
so, the system has one solution
these lines intersect at (20,-40)
+graph%28+600%2C+600%2C+-55%2C+55%2C+-55%2C+55%2C+-2x%2C-3x%2B20%29+