Yr 9 Unit4 Week 1 - Lesson 2

• Mathematics
• Lower Secondary (Key Stage 3)

Yr 9 Unit4 - Lesson 2

Substitution And Solving 

In your exercise book:

• TITLE - Unit 4 - Week 1 - SUBSTITUTION AND SOLVING
• INSTRUCTIONS - Write the questions in your book and answer. 
• QUESTIONS -  1 and 2

ANSWERS

Select the answers that show that the left hand side of the equation is equal to the right hand side

1. 1 + 2 + 3 = 3 + 2 + 1
2. 1 + 2 = 2 + 1
3. a + b = b + a
4. a + b + c = b + a

Select the correct value for y = 2x + 3 when x = 2

1. 4
2. 7
3. 5
4. None

Select the correct value of x that will cause the equation y = 4x - 2 to equal 23

1. 3
2. 4
3. 5
4. 6

DO NOW  

In your exercise book:

• TITLE - Unit 4 Week 1 - Lesson  2 DO NOW
• INSTRUCTIONS - Write questions on the left hand of the  side in your book and answer. 

Complete the table by dragging and dropping a tick or a cross onto a cell.

You need to check if the values of x and y when substituted into the equations will cause them to balance.

Explain what we mean when we say that an equation is BALANCED

What Does Balanced Mean?

An equation is balanced if the left hand side is equal to the right hand side. Some examples include:

a.  2x = x + x

b.  3x = 12 when x = 4

c.  x + y = 10 when x = 3 and y = 7

Talk Task

Given the equation y - 2x = 9 

Talk Task

Given the equation y - 2x = 9 

when y = 11 and x = 1 ---> (11) - 2 x (1) = 9

Talk Task

Given the equation y - 2x = 9 

when y = 11 and x = 1 ---> (11) - 2 x (1) = 9

when y = 11 and x = 2 --->(13) - 2 x (2) = 9

Talk Task

Given the equation y - 2x = 9 

when y = 11 and x = 1 ---> (11) - 2 x (1) = 9

when y = 13 and x = 2 --->(13) - 2 x (2) = 9

when y = 15 and x = 3 --->(13) - 2 x (3) = 9

Talk Task

Given the equation y - 2x = 9 

when y = 11 and x = 1 ---> (11) - 2 x (1) = 9

when y = 13 and x = 2 --->(13) - 2 x (2) = 9

when y = 15 and x = 3 --->(13) - 2 x (3) = 9

when y = _ _ and x = _ _ --->(_ _) - 2 x (_ _) = 9

when y = _ _ and x = _ _ --->(_ _) - 2 x (_ _) = 9

when y = _ _ and x = _ _ --->(_ _) - 2 x (_ _) = 9

Talk Task

Given the equation y - 2x = 9 

when y = 11 and x = 1 ---> (11) - 2 x (1) = 9

when y = 13 and x = 2 --->(13) - 2 x (2) = 9

when y = 15 and x = 3 --->(13) - 2 x (3) = 9

when y = 17 and x =4  --->(17) - 2 x (4) = 9

when y = _ _ and x = _ _ --->(_ _) - 2 x (_ _) = 9

when y = _ _ and x = _ _ --->(_ _) - 2 x (_ _) = 9

Talk Task

Given the equation y - 2x = 9 

when y = 11 and x = 1 ---> (11) - 2 x (1) = 9

when y = 13 and x = 2 --->(13) - 2 x (2) = 9

when y = 15 and x = 3 --->(13) - 2 x (3) = 9

when y = 17 and x =4  --->(17) - 2 x (4) = 9

when y = 19 and x = 5 --->(19) - 2 x (5) = 9

when y = _ _ and x = _ _ --->(_ _) - 2 x (_ _) = 9

Talk Task

Given the equation y - 2x = 9 

when y = 11 and x = 1 ---> (11) - 2 x (1) = 9

when y = 13 and x = 2 --->(13) - 2 x (2) = 9

when y = 15 and x = 3 --->(13) - 2 x (3) = 9

when y = 17 and x =4  --->(17) - 2 x (4) = 9

when y = 19 and x = 5 --->(19) - 2 x (5) = 9

when y = 21 and x = 6 --->(21) - 2 x (6) = 9

Did you understand how we substituted different values into the talk task exercise and always ended up with the same answer?

Yes I did understand what we did.

I understood some of it but I would like to go over it again.

I did not understand any of it.

For the equation x + 2y = 12, select the correct values of x and y so that the equation balances

1. x = 0 and y = 6
2. x = 12 and y = 0
3. x = 2 and y = 5
4. x = 3 and y = 4

New Learning

Copy the next slide into your exercise book.

INDEPENDENT STUDY  

In your exercise book:

• TITLE - Unit 4 Week 1 - Lesson  2 INDEPENDENT STUDY
• INSTRUCTIONS - Write down the questions in your book and then answer them. 
• QUESTIONS - 1 and 3

Explain what is the meaning of the word equivalent

What would the following equation look like if all the parts in it were doubled:
2x + 3y = 5

What would the following equation look like if all the parts in it were trebled:
2x + 3y = 5

Which of the following equations IS NOT equivalent to
x + 2y = 10

1. x = 10 - 2y
2. 2y = 10 - x
3. x + 2y - 10 = 0
4. x + 10 = 2y

Which of the following equations IS NOT equivalent to
y = 2x + 5

1. 2y = 4x + 10
2. 2y = 3x + 6
3. 3y = 3x + 15
4. 10y = 20x + 50

Which of the following equations IS NOT equivalent to
x = y + 4

1. 2x = 2y + 4
2. x - y = 4
3. x = 4 + y
4. 3x = 3y + 12

INDEPENDENT STUDY  

In your exercise book:

• TITLE - Unit 4 Week 1 - Lesson  2 INDEPENDENT STUDY
• INSTRUCTIONS - Write down the questions in your book and then answer them. 
• QUESTIONS - 1 and 3