SOLUTION: Hey there, I have been given a simultaneous equations hwk, and have been doing fine up till now, where I cannot get passed. Here follows 2 examples of the questions that I am strug

Algebra ->  Linear-equations -> SOLUTION: Hey there, I have been given a simultaneous equations hwk, and have been doing fine up till now, where I cannot get passed. Here follows 2 examples of the questions that I am strug      Log On


   

Question 1015340: Hey there, I have been given a simultaneous equations hwk, and have been doing fine up till now, where I cannot get passed. Here follows 2 examples of the questions that I am struggling with: 3y-x=15 and 2x%2By=-2 is the first set, the 2nd is 4y-2x=22 and 3x%2B2y=7. I know that I must rearange one equation and then solve through substitution here's what I get, 3y=15-x this I need to sub in, but the other equation only has 1y not 3y, so I do not know how to get rid of this 3y to make it equal 1! Thanks for reading!
Answer by ikleyn(52781) About Me  (Show Source):
You can put this solution on YOUR website!
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Hey there, I have been given a simultaneous equations hwk, and have been doing fine up till now, where I cannot get passed. Here follows 2 examples of the questions that I am struggling with: 3y-x=15 and 2x%2By=-2 is the first set, the 2nd is 4y-2x=22 and 3x%2B2y=7. I know that I must rearange one equation and then solve through substitution here's what I get, 3y=15-x this I need to sub in, but the other equation only has 1y not 3y, so I do not know how to get rid of this 3y to make it equal 1! Thanks for reading!
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1.

3y - x = 15    (1)
2x + y = -2    (2)


Express x from (1): x = 3y - 15, and substitute it into (2).


Please complete it yourself.

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2.

4y - 2x = 22    (1)
3x + 2y =  7    (2)

Express 2y via x from (2): 2y = 7 - 3x, and substitute it into (1).


Please complete it yourself.