Correct way to solve

Question

Solve

 

9y-2X= -7

X-3y= 5

Answer 1

Hi Amanda,

 

          9y-2X= -7
           X-3y= 5

 

 

Before starting to solve this system of equations, you want to make sure that the variables are in the same order for both equations.  So the first equation is now:

 

                          -2x+9y = -7

 

Now we have:     -2X+9y= -7
                          x-3y= 5

 

 

Solving the system by Elimination, multiply the 2nd equation by 2 and then add the equations together.

 

 

               -2X+9y= -7
                2[x-3y= 5]

 

              -2X+9y= -7
                2x-6y= 10

                     3y = 3

                       y=1

 

Substitute y=1 into one of the equations to find the x-value.

 

                   x-3y = 5

                   x -3(1) =5

                   x-3=5

                    x=8

 

The solution to the system is x=8 and y=1   

 

The solution can also be written as a point, (8,1).  Why?  Because the solution is the point where the two linear equations intersect graphically.