Y7MA4_Formulae_4_01_2012

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Algebraic terms and expressions : 

Algebraic terms and expressions Lesson objective: To be able: to understand and use formulae [Level 5] Key words: formulae Starter: Write down some words for the meaning of the following: a) Variable b) Term, c) Expression

Slide 2: 

Variable: A symbol(letter) for a number that we do not know yet. e.g. x, y , n, t. Term: An algebraic quantity with variables and numbers . e.g. 3x, n/2, y2 Expression: A combination of variables, numbers and signs. e.g. 8-n, 2x-3, 2y+7-t

Identify the variable, term and expression… : 

Identify the variable, term and expression… Variable Term 4x – 7 = 5 Expression

Slide 4: 

What is formula???? Formula is a rule which helps you to calculate some quantity.

Slide 5: 

Example 6.3 The cost of hiring a hall for a wedding is £200 plus £6 per person. Find the formula/rule to calculate the cost. The cost (c) for 1 person is The cost (c) for 2 people is The cost (c) for 3 people is The cost (c) for n people is …… 200+6x1 200+6x2 200+6x3 200+6xn

Slide 6: 

Therefore, the rule, written as a formula is: c = 200 + 6n, where c = cost in £ n = number of people

Slide 7: 

Use the formula c = 200 + 6n to calculate the cost of a wedding with 70 people. Cost = c = 200 + 6 x 70 = 200 + 420 = £620

Work in pairs… : 

Work in pairs… c = 2 x h D = J + 40 c = 3+2x5=13 c = 3+2x3=9 c = 3+2x8=19 c = 8+5x1=13 c = 8+5x3=23 c = 8+5x7=43

Plenary : 

Plenary s = number of sweets in the box If I add 2 how many? s + 2 If I add 4 more, how many? s + 2 + 4 = s + 6 If I then eat 10, how many? s + 6 – 10 = s – 4 How many in 2 boxes? s + s = 2 x s = 2s How many in 11 boxes? 11 x s = 11s How many in 3 boxes, then I eat 7? 3s -7

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