elimination method

Question

Solve : 2x+3y=9

           -3x+3y=-6

 

Using the elimination method 

 

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Answer 1

Hi Briana,

 

We have the system of equations

 

2x+3y = 9

-3x+3y= -6

 

The key to the elimination method is to "eliminate" one of the variable.  We can multiply the 2nd equation by -1 which will give us +3y in the first equation and -3y in the 2nd equation.  Then, if we add the two equations together, we will eliminate the y term.

 

2x+3y = 9

(-3x+3y= -6)(-1)

 

2x+3y = 9
3x-3y= 6

 

5x = 15

x = 3

 

Evaluate one of the original equations at x=3 and solve for y

2x+3y = 9
2(3) +3y = 9

6+3y=9

3y=3

y=1