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

Question

Solve each by substitution

Answer 1

3x + 2y = -2

2x - 4y = -6

 

In 2nd equation factor out 2 on left side:

2(x - 2y) = -6

divide both sides by 2

x - 2y = -3

add 2y to both sides

x = 2y - 3

 

Substitute 2y-3 in place of x in one of the original

equations.  Let's use equation 1.

 

3x + 2y = -2

3(2y-3) + 2y = -2

6y - 9 + 2y = -2

8y - 9 = -2

add 9 to both sides

8y = 9-2

8y = 7

divide both sides by 8

y = 7/8

 

x = 2y - 3

x = 2(7/8) - 3

x = 7/4 - 3

x = 7/4 - 12/4

x = -5/4

 

 

x = -5/4, y = 7/8

 

Check answer by plugging these values into the

original equations to determine if they work.