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Prof.ssa Barbara di Majo in collaborazione con Prof.ssa Cinzia Calella Istituto Tecnico Commerciale “G. R. Carli” Trieste e Prof.ssa Patrizia Torelli Prof.ssa Barbara Fasano Istituto Tecnico Nautico “T. di Savoia” Trieste.
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Prof.ssa Barbara di Majo in collaborazione con Prof.ssa Cinzia Calella Istituto Tecnico Commerciale “G. R. Carli” Trieste e Prof.ssa Patrizia Torelli Prof.ssa Barbara Fasano Istituto Tecnico Nautico “T. di Savoia” Trieste PROGETTO CLIL2006 – 2007EXPONENTIAL AND LOGARITHMIC FUNCTIONS
EXPONENTIALS AND LOGARITHMS • WHO: IV CLASS • WHEN: I TERM • TIME: 8-10 HOURS
AIMS Students should : • Improve their abilities with numbers and symbols • Understand some practical applications of maths
OBJECTIVES • To work with powers, roots, logarithms • To revise and use some topics studied in the I and II class • To draw exponential and logarithmic functions
CONTENTS • Powers (revise) • Exponential and logarithmic functions • Logarithms • Tasks • Practical application
PREREQUISITES Students should know: • Powers of numbers and their properties • Coordinates
LESSON 1 Objective: to encourage students to read and speak Time: 1 h (task included)
VOCABULARY potenza power base base a alla n a to the n esponente exponent/index per times più plus meno minus diviso divided
radice root radice quadrata square root radice cubica cube root alla seconda squared alla terza cubed elevare to raise to inversa inverse logaritmo logarithm log in base 10 common logarithm log naturale natural/neperian log
Task: singular work Every student should create a sentence using one of the words of the glossary (except for the last 3) and report to the whole class
LESSON 2 Objective: to revise the powers (contents studied in the I and II class) Time: 1 h (task included)
WHAT ARE POWERS? There are many particular multiplications in which all the factors are all the same For example: 2·2∙2·2·2 Not to write in a such long way, it has been introduced a new mathematical operation: the power So 2·2·2·2·2 is written as 25
Task: individual work Each student should create an example of the previous properties and report to the whole class
Indicate if every raltionship is true or false: 1. 53 = 15 T F 2. 24 = 16 T F 3. T F 4. (53)7 = 521 T F 5. 00 =1 T F 6. 83 : 83 = 0 T F 7. (73 : 72)0 = 1 T F 8. (142 : 72) = (14 : 7)2 T F 9. (153 : 33) = 125 T F 10. (24)3 : (24)2 = 16 T F 11. (34)2 3 = 39 T F 12. 23 25 : 22 : 28 = 2-2 T F
1. 2. 3. 4. Calculate the value of these expressions using powers properties:
LESSON 3 Objective: • To draw “a raised to the power of x” • To understand the characteristics of these functions Time: 2h
First task (individual or pair work) Calculate the values of the function giving to x positive and negative values
Remember! Properties of the power of the numbers:
Second task (individual work) Calculate the values of the function giving to x positive and negative values
Third task (small groups) • Draw the two functions on the same Cartesian Plane • Compare your results • Describe their properties
Plenary lesson The teamleaders of the groups report their conclusions to the whole class
Properties • Increasing • Continue • Asymptote: x axis • Positive
LESSON 4 Objective: to work with logarithms Time: 2 h (task included)
We call logarithm of bin base a logarithms the exponent x we give to the base a to obtain the number b
x = loga b • ax = b • base
Changing the base of a logarithm logac = x → c ≡ ax so logbc ≡ logbax ≡ x·logba
Therefore or
Task: (individual work):Calculate (remember the properties!) 1. log (3xy) 6. log 2. log (a2bc3) 7. log 3. log 8. log 4. log 9. log 5. log 10. log
Semplify: 1. log x – log y – log z 2. 2log a + 3log b – 5log c 3. log x + log y - log z 4. 2log a –log a3 5. log 16 – 3log 2 + log 4 6. log 27 – log 5 + log 3 7. 8.
LESSON 5 Objective: • to apply the definition of logarithm • to draw logarithmic functions • to understand their carachteristics Time: 2 h
First task (in pairs) Calculate the values of the functions and draw them on the same cartesian plane giving to x positive values only
Second task (small groups) • Draw the two functions on the same cartesian plane • Compare your results • Describe their properties
Exponential equations • You are dealing with an exponential equation when the unknown is at the exponent. So, in general, an exponential equation is presented in the form: ax=b
How to solve it? As you certainly remember, to solve an equation, you pass through inverse operations (in both member of the equation), in order to semplify it. • For example: • x+3=5 x=5-3 - is the inverse operation of + • 5x=15 x=15:5 : is the inverse operation of • • x=32 the power is the inverse operation of , the unknown is the base
So, if the unknown is at the exponent…try to guess how to solve it: which is the inverse operation of the power when the unknown is at the exponent? ax=b so logax=logb and, using the logarithmic properties: xloga=logb so
First task • Try to solve the following exponential equations using the logarithms and their properties:
Can you guess how to solve simplier if you have just powers of the same base? And can you try to solve equations like these?
LESSON 6 Objective: to connect maths with other disciplines Time: 1 h
Applications of exponential equations in financial mathematics • Glossary • Linear capitalization law • Exponential capitalization law • Searching for the time in the capitalization law
Glossary Matematica finanziaria = financial mathematics Interest rate = tasso di interesse Montante = total amount Valore attuale = current value
Linear capitalization law • In the linear capitalization law, interests are always proportional to the time and the nominal value of the capital • I = i C t where: • I = interest • i = interest rate • C = nominal value of the capital • t = time • So M=C+Cit=C(1+It) Where M = final amount
Exponential capitalization • In the esponential capitalization the total amount is calculated on the total amount of the previous year 0 1 2 M=c M1=C+Ci M2=M1+M1i M1=C(1+i) M2=M1(1+i) M2=c(1+i)(1+i) M2=C(1+i)2