SOLUTION: Solve the following by substitution 2x-y=10 x=-2y

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons  -> Quadratic Equation Lesson -> SOLUTION: Solve the following by substitution 2x-y=10 x=-2y      Log On


   

Question 178718: Solve the following by substitution
2x-y=10
x=-2y
Answer by jojo14344(1513) About Me  (Show Source):
You can put this solution on YOUR website!

2x-y=10, EQN 1
x=-2y, EQN 2
Subst. EQN 2 in EQN 1:
2%28-2y%29-y=10
-4y-y=10
-5y=10--------->cross%28-5%29y%2Fcross%28-5%29=cross%2810%292%2Fcross%28-5%29
highlight%28y=-2%29, subst. in EQn 2:
x=-2%28-2%29=highlight%284=x%29
Check via EQN 1:
2%284%29-%28-2%29=10
8%2B2=10
10=10
Thank you,
Jojo