system of linear equations?

Question

3x+5y=-17
2x+4y=6

What equation did Bob have after he eliminated x?

Answer 1

To "eliminate" the x values, they must be opposites.

But as they stand right now 3x is not the opposite of 2x.

 

I want to make them opposites. So making them a common multiple

would be 6. If I multiply 3x by -2, I get -6x

and if I multiply 2x by 3 I get 6x....now they are opposites.

 

Just remember to multiply the entire equation by the -2 and 3

like this.....

 

-2(3x + 5y) = -2(-17)  

3(2x + 4y) = 3(6)              The equations now become...

--------------------------

 

 

-6x -10y = 34

6x + 12y = 18                  Add vertically 

--------------------            

 

     2y = 52

       y = 26