Lesson on Substitution Method of Solving Equations

Learning

Goal

8

Let’s solve systems of
equations algebraically

Unit 4 ● Lesson 14

8

Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Open Up Resources, with adaptations CC BY Illustrative Mathematics.

Yesterday we looked at Substitution…

And More…

Substitution can also show
up more intensely that what
we’ve seen.

BUT

The process is still the same!

8

Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Open Up Resources, with adaptations CC BY Illustrative Mathematics.

Try One

9y = 4x - 3

x = 2y + 1

Identify

ONE

variable

Substitute

Solve

Plug solution
in to check if

it’s correct

Multiple Choice

Use Substitution to solve each system of equations:

y = 5x + 1

4x + y = 10

• x = 1, y = 6
• x = 4, y = 9
• Infinite Solutions

• x = 2, y = 7

Multiple Choice

Use Substitution to solve each system of equations:

2y+ 4x=10

y=-2x+7

• Infinite Solutions

• x=0, y=5
• x=1, y=3
• No Solutions

Multiple Choice

Use Substitution to solve each system of equations:

y = 4x - 1

2x + y = 17

• x = 3, y = 11
• x = 7, y = 8
• x = 2, y = 14
• x = 5, y = 9

Multiple Choice

Use Substitution to solve each system of equations:

y=3-2x

4x+4y=8

• The solution is (1 , 1)

• No Solutions

• The solution is ( 3 , 3).

• The solution is ( 2 , 2)

Multiple Choice

Use Substitution to solve each system of equations:

3x+4y=-5

x=-3-2y

• No Solutions

• x = -3, y = 0
• x = 4, y = 2
• x = 1, y = -2

Multiple Choice

Use Substitution to solve each system of equations:

y=2x+4

y-2x=4

• x=4, y=0
• No Solutions

• x=3, y=6
• Infinite Solutions

Multiple Choice

Use Substitution to solve each system of equations:

y=-3x+4

-6x-2y=-8

• The solution is ( 0 , 4)

• The solution is ( 2 , -2 )

• The solution is ( 3 , -3).

• The solution is ( -2 , 2).

Multiple Choice

Use Substitution to solve each system of equations:

x=y-1

-x+y=-1

• The solution is (1 , 2)

• The solution is ( 0 , 1)

• Infinite Solutions

• The solution is ( -1 , 0)

1. Without solving, identify 3 systems that you think would be the least difficult to solve and 3 systems that you think would be the most difficult to solve.

2. Choose 1 to solve now!