October 4, 2012

Brackets and factors



   1. Brackets




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Explanation             October 4, 2012

Look at this shape…
                  2              8

             2


You can work out the total area by calculating 2 × (2 + 8)
This is equal to 2 × 2 plus 2 × 8 or 4 + 16
The same is true in algebra
a(b + c) means       “add b and c, then multiply by a”.
This is the same as “multiply a by b and multiply a by c,
                     then add the two results”.
                                                        More
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Example                  October 4, 2012

Multiplying to get rid of the brackets in 2 × (2 + 8)
to make 2 × 2 + 2 × 8 is called expanding.

Once you have got rid of the brackets by expanding,
you can simplify, or group things that are the same.
Remember, there are certain general simplifications…
             2×a      should be written 2a
             a×a      should be written a ²
             a×b      should be written ab
                             so
       2 × (2 + 8)   could be expanded as 2² + 16
 and a × (a + 8)     would be expanded as a² + 8a
                                                           More
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Practise             October 4, 2012

Expand and simplify as far as you can the following…
2(a + 1)                      2a + 2

3( x – 2)                     3x – 6
2a (a – 1)                    2a² – 2a

2b (a – b )                   2ab – 2b²
2ab(a – b )                   2ba² – 2ab²
2 (2x + y ) + 2 (2x + 2y )    4x + 2y + 4x + 4y      8x + 6y
A group of numbers and letters, such as 4b, 2y or 3x²
is known as a term.
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                                                            Next
                                                            End

Brackets

  • 1.
    October 4, 2012 Bracketsand factors 1. Brackets Next
  • 2.
    Explanation October 4, 2012 Look at this shape… 2 8 2 You can work out the total area by calculating 2 × (2 + 8) This is equal to 2 × 2 plus 2 × 8 or 4 + 16 The same is true in algebra a(b + c) means “add b and c, then multiply by a”. This is the same as “multiply a by b and multiply a by c, then add the two results”. More Next
  • 3.
    Example October 4, 2012 Multiplying to get rid of the brackets in 2 × (2 + 8) to make 2 × 2 + 2 × 8 is called expanding. Once you have got rid of the brackets by expanding, you can simplify, or group things that are the same. Remember, there are certain general simplifications… 2×a should be written 2a a×a should be written a ² a×b should be written ab so 2 × (2 + 8) could be expanded as 2² + 16 and a × (a + 8) would be expanded as a² + 8a More Next
  • 4.
    Practise October 4, 2012 Expand and simplify as far as you can the following… 2(a + 1) 2a + 2 3( x – 2) 3x – 6 2a (a – 1) 2a² – 2a 2b (a – b ) 2ab – 2b² 2ab(a – b ) 2ba² – 2ab² 2 (2x + y ) + 2 (2x + 2y ) 4x + 2y + 4x + 4y 8x + 6y A group of numbers and letters, such as 4b, 2y or 3x² is known as a term. More Next End