The document discusses using algebraic expressions and substitution. It provides examples of evaluating expressions where a variable is replaced with a number. These include expressions like h + 5 for h = 3, 2y + 7 for y = 4, and 3a - 2b for a = 10 and b = 4. The steps shown are writing the expression, replacing the variable with the given number, and calculating the final numerical answer. Completing a table using the rule y = 3x - 1 is also demonstrated.

1. Image Source: http://photos.northofboston.com

2. In Basketball we can have certain set positions on
the court, and substitute player names into these
positions.
This gives us one unique team who will play for us
during the match.
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(See next Slide for example).

3. Rufas
Leroy
Tyrone
Willy
Wally

4. We could choose a different team with some
different player names, and this would give us a
different result.
Our Team Positions chart sets up where we can
substitute our players, and we can pick several
different names to substitute into this chart.
In Algebra, we have an “Expression” that tells us
what different variable letters we have available to
substitute numbers into.
The Algebra Expression is like our “Panthers”
team Basketball Positions Chart.
It sets up what we can substitute our values into.

5. Here is a basic substitution question:
Evaluate the expression h + 5 for h = 3 .
(“Evaluate” means work out the number answer)
The steps for evaluating are as follows:
 Write down the Algebraic Expression
 Replace the letter with the number value
 Work out the final number answer.
(Continued on next slide)

6. Evaluate the expression h + 5, for h = 3
The expression is: h + 5
We need to replace the “h” with 3
This makes: 3+5
which equals: 8
(Continued on next slide)

7. Evaluate the expression h + 5, for h = 3
We set this out in our math workbook as like this:
h + 5 (h=3)
=3+5
=8

8. Evaluate the expression 2y + 7, for y = 4
We need to replace the “y” with the number 4.
2y + 7 (y = 4)
= 24 + 7
= 31
2y means 2 multiplied by y - We have made an error. 

9. Evaluate the expression 2y + 7, for y = 4
2y + 7 (y = 4)
2y means 2 x y
= 2 (4) + 7
= 8 +7
= 15

10. Evaluate 3a - 2b, for a = 10 and b = 4
3a – 2b (a = 10 b = 4)
= 3(10) – 2(4)
= 30 – 8
= 22

11. Evaluate a / 2b + c, for a = 10 b = 1 c = 4
a / 2b + c (a = 10 b = 1 c = 4)
= 10 / 2(1) + 4
= 10 / 2 + 4 (Divide before Adding)
= 5 + 4 = 9

12. Evaluate a(ab + c), for a = 2 b = 3 c = 5
a ( ab + c ) (a = 2 b = 3 c = 5)
= 2 ( 2(3) + 5 ) (Do inside first)
=2( 6 + 5) (Keep doing Inside)
=2( 11 ) = 2 x 11 = 22

13. Complete the following table using the
rule: y = 3x - 1
x y We need to use the expression
3x - 1 to work out each y value.
2
4 Eg. For x = 2
6
3x – 1
8
= 3(2) – 1
= 6 – 1
= 5 (See next Slide)

14. Complete the following table using the
rule: y = 3x - 1
x Working Out Steps y
2 y = 3x -1 = 3(2) – 1 = 6-1 = 5 5
4 y = 3x -1 = 3(4) – 1 = 12-1 = 11 11
6 y = 3x -1 = 3(6) – 1 = 18-1 = 17 17
8 y = 3x -1 = 3(8) – 1 = 24-1 = 23 23

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