help answerin problem substitution technique

Question

Y=2x+3

-4x-4y=12

 

 

Answer 1

y = 2x + 3
-4x - 4y = 12

 

Since y = 2x+3, substitute 2x+3 in place of y in the second equation and solve for x:

 

-4x - 4y = 12

-4x - 4(2x+3) = 12

-4x - 8x -12 = 12

-12x = 24

x = -2

 

Now solve for y:

y = 2x + 3

y = 2(-2) + 3

y = -4 + 3

y = -1

 

Check:

y = 2x+3

-1 = 2(-2)+3

-1 = -4+3

-1 = -1    Check!

 

-4x-4y = 12

-4(-2) - 4(-1) = 12

8 + 4 = 12

12 = 12    Also Check!