Solving by Substitution Method Steps

The first step in solving using the substitution method is __________.

• get x by itself

• get y by itself

• get either variable by itself

• add the equations together

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Step 3: After substituting the first equation into the second one and working it out, I got x = 1. What should I do next? Then do it.

• Fill in 1 for x in y = 6x y = 6(1) y = 6

• Fill in 1 for y in y = 6x 1 = 6x 1/6 = x

• Fill in 1 for y in 2x + 5y = 32 2x + 5(1) = 32 2x + 5 = 32 2x = 27 x = 27/2

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Example 1

Step 4:

What is the solution to the system:

y = 6x

2x + 5y = 32

Given I got x = 1 from step 2 and y = 6 from step 3.

• (1, 6)

• (6, 1)

Tags

CCSS.HSA.REI.C.7

Using substitution, what is the correct next step? I am not interested in the answer.

• 5x - (2x) = 9

• 5(2x) - y = 9

• (3,6)

• (6,3)

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Using substitution, what is the correct next step? I am not interested in the answer.

• 3x - 7(-2y-21) = 41

• 3(-2y-21) - 7y = 41

• -2(41-3x) - 21

• (-5,-8)

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Solve this system by substitution.

• (1, -4)

• (1, 4)

• (-4, -7)

• (-7, -4)

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

• No solution

• Infinitely many solutions

• (-3,7)

• (-2,-6)

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

What is the solution to this system? Solve by substitution.
y= 4x + 3
2x - 3y = 21

• (3,-9)

• (-3,-9)

• (-3,9)

• (0,1)

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Example 2:

x - y = 0

18x + 2y = 0

Which statement would be correct for step 1 and do it?

• I would solve the first equations for y because it has a coefficient of 1.

  y = -x

• I would solve the first equations for y because it has a coefficient of -1.

  -y = -x

• I would solve the first equations for x because it has a coefficient of 1.

  x = y

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

In step 1, we got x = y.

Which shows the correct steps for step 2 (substituting and solving)?

• 18x + 2y = 0

  18(y) + 2y = 0

  20y = 0

  No Solution

• 18x + 2y = 0

  18(y) + 2y = 0

  20y = 0

  y = 0

Tags

CCSS.8.EE.C.8B