Question

guys i need help with checking my work for the elimination. i got y=4 , x=1. equation : 3x-2y=5 and 6x-4y=-10. how do i substitute the value for x and y in this equation to check if my answer is correct or wrong. show your work.

Answer 1

3(1) - 2(4) = 5
    3  - 8      =5
                -5 = 5   < your answers are incorrect because -5 is not equal to a positive 5. 

try doing it this way:

so your equations are
3x - 2y = 5    and 
6x - 4y = -10

multiply the first equation by 2 so it becomes
6x + 4y = 10 
then you add the two equations

6x + 4y = 10
6x - 4y = -10
------------------
12x       = 0
           x = 0

then you plug 0 into any one of the previous equations that we started off with
I will use: 3x - 2y = 5

3(0) - 2y = 5
0 - 2y = 5
-2y = 5 - 0
    y = 5/-2   or -2 1/2
   
you can check by adding the x value = 0  and the y value = -5/2 into any one of the previous equations 

I will use: 6x - 4y = -10

6(0) - 4(-5/2) = -10
     0 - (20/2) = -10
               -20/2 = -10
                  -10 = -10

hope this helps :)