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Determine the number of solutions to the system:

2x+6y=18

-3x-9y=-27

 

And if possible, please show me how you came up with the answer!

 Feb 25, 2019
 #1
avatar+100570 
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2x + 6y= 18

-3x - 9y= -27

 

To make this easier  divide the first equation through by 2    and the second through by 3 and we have that

 

x + 3y   =  9

-x - 3y  = - 9          add these

 

0 = 0

 

When we have this situation.....there are infinite solutions  for (x, y)

 

For instance   (0, 3)  solves the equations

or

(9, 0)  also   works

 

This is actually the same line....mutiply the second equation by -1  and we get

 

x + 3y = 9       the same as the first equation  !!!

 

 

cool cool cool

 Feb 25, 2019

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