SOLUTION: A student is using the elimination method to solve the system of equations below. What is the best first step? 5x - 2y = -15 3x + 3y = 12

Algebra ->  Coordinate Systems and Linear Equations -> SOLUTION: A student is using the elimination method to solve the system of equations below. What is the best first step? 5x - 2y = -15 3x + 3y = 12      Log On


   

Question 1015677: A student is using the elimination method to solve the system of equations below. What is the best first step?

5x - 2y = -15
3x + 3y = 12
Found 2 solutions by josgarithmetic, addingup:
Answer by josgarithmetic(39618) About Me  (Show Source):
You can put this solution on YOUR website!
Multiply the members of the first equation by 3; and multiply the members of the second equation by 2. The equivalent system can be 15x-6y=-45%2C6x%2B6y=24.

That is one way to begin, but you could choose to prepare to eliminate the other variable instead.

Answer by addingup(3677) About Me  (Show Source):
You can put this solution on YOUR website!
5x - 2y = -15 Multiply times 3
3x + 3y = 12 Multiply times 2
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15x-6y = -45
+
6x+6y = 24
------------
21x = -21 Divide both sides by 21
x = -21/21= -1
Now you can find y:
5x-2y = -15
5(-1)-2y = -15
-5-2y = -15
-2y = -10 Divide both sides by -2, and remember -/- = +
y = 5
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Now you can check your results:
5x - 2y = -15, 5(-1)-2(5)= -15, -5-10 = -15 Correct
3x + 3y = 12, 3(-1)+3(5) = 12, -3+15 = 12 Also correct
J