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

Question

use the elimination method to solve the system

Answer 1

 2x - 2y = -3

-4x + 4y = 6

 

Multiply the first equation by 2:

 

2*(2x - 2y = -3) = 4x - 4y = -6

 

Now add this to the second equation:

 

  4x -  4y = -6

 -4x + 4y =  6

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

   0  +  0  = 0

 

This is a dependent solution, meaning that the two equations are the same line.  All points along the lines are thus solutions.

Answer 2

Hi Devin, using the elimination method results in 0 = 0, or an infinite number of solutions. Lets check:

 

  2x  - 2y  = -3

-4x  + 4y  =  6

 

If we multiply the first equation by 2 gives:

 

 4x   -  4y  = -6

-4x  +  4y  =  6

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

0x  +  0y   = 0

 

These two equations are for the same line. Each line has a slope of 1 and a y-intercept point of 3/2.

 

Questions?