17-Aug-15Created by Mr.Lafferty Maths Dept Formulae Formulae expressed in words Working with...

19 Apr 202319 Apr 2023 Created by Mr.Lafferty Maths DeptCreated by Mr.Lafferty Maths Dept

FormulaeFormulae

Formulae expressed in words

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Working with Expressions

Evaluating Formulae

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Starter QuestionsStarter Questionsw

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2.

2 13. 2 1

3 4

a a d a a d

Simplify

The ratio of apples to pears is 2:5.

I f there are 28 pieces of f ruit in total.

How many apples are there.

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19 Apr 202319 Apr 2023 Created by Mr.Lafferty Maths DeptCreated by Mr.Lafferty Maths Deptww

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2.2. Solving expressions Solving expressions showing working.showing working.

1. To explain the process of working out expressions by Formulae method.

1.1. Understand process of Understand process of Formulae.Formulae.

S4FormulaeFormulae


If a = 3 and b = 9 evaluate

a + b

3 +9=

= 12

Sub in a=3Sub in b=9

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S4FormulaeFormulae



ab

Sub in a=3Sub in b=9

Remember ab means a x b

a x b

3 x 9=

= 27ww

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4b

Sub in b=9

Remember 4b means 4 x b

4 x b

4 x 9=

= 36

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If a = 5 and b = 6 evaluate1. a + b2. ab

3. 3a

4. b - a

5. 4b

6. 3ab

=11=30=15

=1

=24=90w

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S4FormulaeFormulae


If a = 5 and b = 3 evaluate2a +

4bSub in a=5Sub in b=3

Remember 2a means 2 x a

2xa + 4xb

2x5 +4x3

=

=

= 10 + 12= 22

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If a = 5 and b = 3 evaluatea

Sub in a=5

Remember a2 means a x a

a x a

5 x 5

=

=

= 25

2

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aSub in a = 15

153

=

= 5

bSub in b = 3

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If a = 2 and b = 6 evaluate1) 4a +

3b2) a2

3) b2

5) 4a2

4) 5b – 3a

6) ba

=26=

4=36

=24=16

=3

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Now try Ex 1

Ch14 (page 162)

FormulaeS4

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Starter Starter QuestionsQuestions

1. Calculate the area of the following shapes.

2. Round to nearest 100

(a) 47856 (b) 90 (c) 249.5

Q3. Explain why 15% of £ 360 = £ 54

5 cm

2.5 cm 3 cm

4 cm

3 cm

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1. To explain how to work with formulae expressed in words.

1.1. Understand formulae Understand formulae expressed in words.expressed in words.

Formulae

2.2. Solve problems given Solve problems given formulae in words.formulae in words.

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Formulae

A tile fitter charges £20 per hour.

How much will he charge for 8 hours of work.

C = 20xh

For h = 8

C = 20 x 8 =

£160

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Formulae

The cost for hiring a carpet cleaner is

£30 plus £3 a day

How much will it cost to hire for a week.

C = 30 + 3d

For d = 7

C = 30 + 3 x 7 =

£51

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Formulae

Profit :

Subtract how much you paid for goods in the first place from the amount you actually sold them for.

How much profit did Daniel make if he bought a CD for £9.99 and sold it for £12

+

Profit = 12 – 9.99 =

£2.01

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Now try Ex 2

Ch14 (page 164)

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Starter QuestionsStarter Questions

1. Does 3 + 2 x 4 = 11 or 20

212. Calculate of 6

2

3. True or f alse I f a = 9 and b = -3

b b - a = 4

a

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1. To explain how to evaluate formulae

1.1. Understand the term Understand the term formulae.formulae.

Formulae

2.2. Be able to substitute Be able to substitute values into formulae and values into formulae and evaluate properly using evaluate properly using BODMAS.BODMAS.

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Formulae

A formula is the process calculating a quantity based on a known relationship e.g. Length, Area,

Volume etc........It is VERY important that we remember a keypoint

when working with formulae.

BODMAS

Brackets

Other squares and square root etc....

Divide

Multiplication

Addition

Subtraction

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Formula for Parallelogram

Example 1 : Find the area of parallelogram.

Parallelogram Area b h

Area = 9 32Area = 27cm

9cm

3cm

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1r = radius = D

2

3 34Volume = π(10) =4187cm

3

34Volume = πr

3

Formulae for the Volume of a Sphere

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r

D

D = diameter

Q. If the above sphere has radius 10cm.

Calculate it’s volume.

Q. If the above cone has radius 15cm and height

of 10 cm. Calculate it’s volume.

Formulae for Volume of a Cone

h = Perpendicular height

2 31Volume = π(15) 10 = 2355cm

3

r = radius

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r

h21

Volume Cone = πr h3

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Now try Ex 3

Ch14 (page 166)

FormulaeS4

17-Aug-15Created by Mr.Lafferty Maths Dept Formulae Formulae expressed in words Working with...

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