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3-3 The Logic of Equation Solving

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Ithaca High School Lesson Plans

Chapter 3 (PDM)

Lesson Plan 3-3: The Logic of Equation Solving.



Content Standards and Benchmarks:

I,2,3: Expand their understanding of functions to include non-linear functions, composition of functions, inverses of functions, and piecewise and recursively defined functions.

         IV,2,2: Develop an understanding of more complex representations of numbers, including exponential and logarithmic expressions, and select an appropriate representation to facilitate problem solving.



          After reading the lesson the night before, and hearing my short lecture regarding the composition and inverses of functions, students will be able to compose multiple functions and find the inverses of functions.


Anticipatory Set:

          Conversation with the class about the women’s basketball team winning their 7th league game.  Transition to the homework and how no one really likes to work with logarithmic functions.  Transition into what the composition of functions are and how to find the inverse of a function. 



     x has to be an element of the domain of f for f(x) to be defined

     f(x) has to be an element of the domain of g for g(x) to be defined

     The domain of g of f is the intersection of the domain of f and the domain of g

     Function composition is not commutative.

Ex: Gumball machine

     Multiplication and composition looks similar but are very different

     We use function composition to solve equations

     Inverse of a function: if

          f: xy and g: yx, f and g are inverses.

            Continually increasing or decreasing over a

            continuous domain

            Passes Horizontal Line Test and Vertical Line Test

     Limit domains of functions to make their inverses 1-1 functions

     Check for inverses f(g(x)) =g(f(x))



v    Answer student questions from the night before.

v    Tie in today’s objectives with the questions that are asked.


Guided Practice:

v    As the students get more comfortable with the content, I will ask them to lead me through the problems.

v    I may even ask student to come up to the board to do that other students are confused about problems.


Independent practice:

v      Students will be assigned lesson 3-3 to read and do the C.A.R. problems for the next day.



v      “What did we discuss today?”

              How to tell if a function is 1-1

              How to tell if a function has an inverse

              Limit domains to make a function or its

         inverse 1-1

              Function composition is not commutative

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