If you were to use the substitution method to solve the following system, choose the new equation after the expression equivalent to y from the first equation is substituted into the second equation.

5x - y = -6
10x + 4y = -6
Choose one answer. a. 10x + 4(-5x - 6) = -6
b. 10x + 4(5x + 6) = -6
c. 10(-5x - 6) + 4y = -6
d. 10(5x + 6) + 4y = -6

Question

If you were to use the substitution method to solve the following system, choose the new equation after the expression equivalent to y from the first equation is substituted into the second equation. 

5x - y = -6 
10x + 4y = -6
Choose one answer.   a. 10x + 4(-5x - 6) = -6   
  b. 10x + 4(5x + 6) = -6   
  c. 10(-5x - 6) + 4y = -6   
  d. 10(5x + 6) + 4y = -6

ivettef365 · Answer

for the substitution method isolate the y on first equation

5x -y = -6   (first subtract 5x on both sides)
-5x        -5x
-----------
    -y = -5x -6    now just change all signs and you have

     y =  5x + 6   now substitute the y for (5x+6) on the second equation.