SOLUTION: Solve the system by graphing, addition and substitution methods. 3x + y = –1, 9x + 3y = –3

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Question 55065: Solve the system by graphing, addition and substitution methods. 3x + y = –1, 9x + 3y = –3
Answer by rchill(405) About Me  (Show Source):
You can put this solution on YOUR website!
If you add the two together, you get 12x+4y=-4, which reduces to 3x+y=-1. Solving for y we get y=-3x-1. Substituting that value of y into the first equation we get 3x-3x-1=-1 which reduces to -1=-1. Because -1=-1 is a true statement, our answer is correct. The graph of the two equations should be the same line because the 2nd equation reudces to y=-3x-1 also. The graph is:
graph%28200%2C200%2C-5%2C5%2C-5%2C5%2C-3x-1%29