Solving Equations by Substitution Method

Use the system of equations below to answer the question. After substituting the first equation into the second one and working it out, I got x = 1. What should I do next?

• Fill in 1 for x in y = 6x

• Fill in 1 for y in y = 6x

• Fill in 1 for y in 2x + 5y = 32

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

What is the solution to this system?

(Use the substitution method.)

8x - 2y = 6

y = 3x

• (3, 9)

• (5, 2)

• (2, 3)

• (3, 2)

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Solve the system of equations by using the Substitution Method.

y = 2x - 4

7x - 2y = 5

• (-1, -6)

• (-1, -8)

• (-2, 6)

• (1, -8),

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Which answer has a correct next step for this system? (Read all three answers carefully before selecting one!)

• The variable is already isolated, so we've already solved the system.

• The variable is already isolated for y, so we substitute it in the second equation like this:

  2(6x) + 5y = 32

• The variable is already isolated for y, so we substitute it in the second equation like this:

  2x + 5(6x) = 32

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Which answer has a correct next step for this system? (Read all three answers carefully before selecting one!)

• The variable is already isolated, so we've already solved the system.

• The variable is already isolated for y, so we substitute 3x + 5 in the first equation like this:

  3x + 4(3x + 5) = 3

• The variable is already isolated for y, so we substitute 3x + 5 in the second equation like this:

  3(3x + 5) + 4y = 3

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Solve the system by substitution.
 
5x + 4y= −14
y =  −7x  −  15 

• (-2, -1)

• (1, -2)

• (-2, 1)

• (-1, -2)

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Solve the following systems of equations using substitution:

2y + x = -15

x = 3y

• (-3, -9)

• (-9, -3)

• (-3, 9)

• (9, -3)

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Solve the system by substitution. 
y = 2x − 11 
2x − 8y = 4 

•  (6, 1)

• (6, −4)

• (6, −1)

• Infinite number of solutions  

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

x + 2y = 2
x = -4y + 2

• (-3, 0)

• (0, 2)

• (-3, -2)

• (2, 0)

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

7x + y = -20
y = 3x + 10

• (-3, 1)

• (-1, -3)

• (-3,-7)

• (-1,7)

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6