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Ministry of Education Secondary Numeracy Project. Algebra in Multiplication. Kevin Hannah Central Auckland Airport Hotel 23-24 February 2005. Algebra in Multiplication. Computing using the distributive law Recognising structure in numbers Exploring algebraic expressions.
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Ministry of EducationSecondary Numeracy Project Algebra in Multiplication Kevin Hannah Central Auckland Airport Hotel 23-24 February 2005
Algebra in Multiplication • Computing using the distributive law • Recognising structure in numbers • Exploring algebraic expressions
What’s the answer? 7 x 98 How did you do it? 7 x 98 = 7 x 100 - 7 x 2
What’s the answer? 597 x 5 How did you do it? 597 x 5 = 600 x 5 - 3 x 5
What’s the answer? 407 x 8 How did you do it? 407 x 8 = 400 x 8 + 7 x 8
Are these correct? 7 x 98 = 7 x 100 - 7 x 2 915 x 8 = 900 x 8 + 15 x 8 597 x 11 = 600 x 11 - 3 x 7 3x(400-8) = 3x400 - 3x8
Are these correct? 8 x 300 - 7 x 8 = 8 x 293 80 x 7 - 5 x 7 = 85 x 7 79 x 11 = 70 x 11 +9x9 12x40 - 8x12= 8x(40-12)
6 x 600 + 7 x 6 = 6 x 607 80 x 6 - 6 x 6 = 74 x 6 58 x 13 = 50 x 13 + 8 x 13 5x(70-2) =5x70 - 5x 12 What’s missing?
6 ( m + 7) = 6m + 42 8c - 48 = 8(c - 6) 7 ( m + 9 ) = 7m + 63 5(y-2) =5y - 10 Fill in the gaps
5 ( y + 6) = 5y + 30 7(x - 10) = 7x - 70 4 ( 2m + 3 ) = 8m + 12 6(3r-9) = 18r - 54 Expand
3 ( n + 2) = 3n + 6 8(x - 4) = 8x - 32 5 ( 4p + 3 ) = 12p + 15 7(6 - 5y) = 42 - 35y Factorise
Recognising Structure a(b ± c) = ab ± ac