SOLUTION: hello i need help on this question i have to find the solution of 3x+y=9 & 3x-5y=15 but i cant seem to get the solution can you help me thank you (:

Question 1040810: hello i need help on this question i have to find the solution of 3x+y=9 & 3x-5y=15 but i cant seem to get the solution can you help me thank you (:
Found 3 solutions by jim_thompson5910, josgarithmetic, ikleyn:
Answer by jim_thompson5910(35256)   (Show Source): You can put this solution on YOUR website!
Let's call the equations A and B
A: 3x+y = 9
B: 3x-5y = 15

Subtract the equations A - B. To do this, we subtract the like terms on each side
3x - 3x = 0x = 0. The x terms go away
y - (-5y) = y+5y = 6y
9-15 = -6

So after subtracting the equations (A-B) we end up with 6y = -6

Now we divide both sides by 6 to fully isolate y

6y = -6
6y/6 = -6/6
y = -1

Now use this to find x

3x+y=9
3x+(-1)=9 ... replace y with -1
3x-1 = 9
3x-1+1 = 9+1
3x = 10
3x/3 = 10/3
x = 10/3

So,
x = 10/3
y = -1

The solution as an ordered pair is (10/3, -1)
Answer by josgarithmetic(39617)   (Show Source): You can put this solution on YOUR website!
Solve one of the equations for ONE variable in terms of the other variable. SUBSTITUTE this expression in the other equation and solve for the single variable. Go back to the first chosen equation and substitute what you just found for the single variable and solve for the single variable resulting in the first chosen equation.

IF YOU ARE LEARNING the Elimination Method, then the work you are expected to do using your given equations may be easier.

The results you should find are and .
Answer by ikleyn(52777)   (Show Source): You can put this solution on YOUR website!
.
hello i need help on this question i have to find the solution of 3x+y=9 & 3x-5y=15 but i cant seem to get the solution can you help me thank you (:
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Now, when the tutors just explained you almost everything, I'd like to give you the links to lessons
on solving linear systems with 2 equations in 2 unknowns in this site:
    - Solution of the linear system of two equations in two unknowns using determinant
    - Solution of the linear system of two equations in two unknowns by the Substitution method
    - Solution of the linear system of two equations in two unknowns by the Elimination method
    - Geometric interpretation of the linear system of two equations in two unknowns

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