SOLUTION: I need help solving by substitution 6y=21-3x x+2y=5

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Question 88377: I need help solving by substitution
6y=21-3x
x+2y=5
Answer by checkley75(3666) About Me  (Show Source):
You can put this solution on YOUR website!
X+2Y=5 OR X=5-2Y NOW WE SUBSTITUTE (5-2Y) FOR X IN THE OTHER EQUATION & SOLVE FOR Y.
6Y=21-3(5-2Y)
6Y=21-15+6Y
6Y-6Y=6
0=6 THUS THERE ARE NO SOLUTIONS TO THESE TWO EQUATIONS.
PROOF
WE'LL CONVERT THESE TWO EQUATIONS TO THE LINE FORMULA & PLOT TO SEE IF THEY INTERSECT.
6Y=21-3X OR 6Y=-3X+21 OR Y=-3X/6+21/6 OR Y=-X/2+3.5 (RED LINE)
X+2Y=5 OR 2Y=-X+5 OR Y=-X/2+5/2 OR Y=-X/2+2.5 (GREEN LINE)
+graph%28+300%2C+200%2C+-6%2C+5%2C+-10%2C+10%2C+y+=+-x%2F2+%2B3.5%2C+y+=+-x%2F2+%2B2.5%29+ (graph 300x200 pixels, x from -6 to 5, y from -10 to 10, of TWO functions y = -x/2 +3.5 and y = -x/2 +2.5).