SOLUTION: My question is based on solving systems of equations by way of substitution x+2y=4 4y=-2x-8 I know how to do this, but I keep on coming up with the wrong answer?

Algebra ->  Exponents-negative-and-fractional -> SOLUTION: My question is based on solving systems of equations by way of substitution x+2y=4 4y=-2x-8 I know how to do this, but I keep on coming up with the wrong answer?      Log On


   

Question 1000185: My question is based on solving systems of equations by way of substitution
x+2y=4
4y=-2x-8
I know how to do this, but I keep on coming up with the wrong answer?
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
Knowing how to do it, you will solve the problem as you want and without the mistake you are making.

The equivalent system is system%28x=4-2y%2C2y=-x-4%29 and the substitution was not yet done.

2y=-%284-2y%29-4
2y=-4%2B2y-4
2y=2y-8, a false statement.
NO SOLUTION.


Notice the two equations solved for y in terms of x, starting with the way each was given:
x%2B2y=4
2y=-x%2B4
y=-x%2F2%2B2
y=-%281%2F2%29x%2B2
-
4y=-2x-8
y=-2x%2F4-2
y=-%281%2F2%29x-2
-
BOTH SLOPES are -1%2F2, the lines for each equation are parallel, therefore they never intersect, and this means NO POINT COMMON TO BOTH LINES.

Meaning, solving the given system using whatever method will yield NO SOLUTION.