Do Now
Solve the Puzzle!
LO:
To be able to expand a single bracket
SC:
Use grid method to:
Multiply numbers together
Multiply numbers and letters
Brackets are a way of keeping things together
Think of brackets as being a bag, to hold things together
(2x + 4)
Multiplying Brackets
When we write a number next to a bracket, we multiply that number by everything in the bracket
Example:
3(2x + 4)
3 x 2x + 3 x 4
Grid Method
We can use Grid Method to complete this sort of sum
3(2x + 4) We split up the bracket into two separate terms, 2x and 4
| 2x | 4 |
3 | | |
Grid Method
We can use Grid Method to complete this sort of sum
3(2x + 4)
3 x 2x goes in this box
3 x 2 = 6 then add
the x
| 2x | 4 |
3 | 6x | |
Grid Method
We can use Grid Method to complete this sort of sum
3(2x + 4)
3 x 4 goes in this box
3 x 4 = 12
| 2x | 4 |
3 | 6x | 12 |
Grid Method
We can use Grid Method to complete this sort of sum
3(2x + 4)
Our final answer is 6x + 12
| 2x | 4 |
3 | 6x | 12 |
Grid Method
We can use Grid Method to expand brackets with a letter instead of a number too:
b(2a + 3)
The final answer is: 2ab + 3b
| 2a | 3 |
b | 2ab | 3b |
Multiplying Positives and Negatives
Just like when adding and subtracting positives and negatives, there are rules for multiplying positives and negatives
When two positives are multiplied together (+ x +) the answer is positive (+)�2 x 2 = 4
When two negative are multiplied together (- x -) the answer is positive (+)� -3 x -2 = 6
When a negative and positive are multiplied together (+ x -) or (- x +), the answer is negative (-)
-3 x 4 = -12 OR 5 x -4 = -20
| x | 3 |
4 | 4x | 12 |
| x | -5 |
-2 | -2x | 10 |
4x + 12 - 2x + 10
2x + 22
4(x + 3) - 2(x – 5)
We can use the grids to expand brackets and then collect the like terms
Workspace: Algebra - Term 2
Slide 1: Numbers
Slide 2 Letters
Slide 3 Letters and Numbers
Slides 4-6 Numbers (2 brackets)
Slides 7-9 Numbers and Letters (2 � brackets)
Slide 10 MyMathsOnline and Transum