Sept. 14 Class

Learning Goals: Understand how to denote the domain and range of a quadratic equation.

Today I handed back the formative quizzes.  You can download a copy of the solutions here:

Formative Quiz 1 Solutions

Next I reviewed how to write down the domain and range of various functions. If the function is given as a set of ordered pairs, we just need to list the values,

Example: What is the domain and range of the following function,

(2, 3)  (3,6)  (4, 8)  (5, 3)  (6, 3)

Solution: D = {2, 3, 4, 5, 6}  R = {3, 6, 8}

If we have a graph the domain and range is a bit more tricky.

Example: What is the domain and range of the following function?

Solution: The domain, x,  can be any value.  In set notation we write this as,

In words, we read this as "The domain is x in the real numbers".

The range, y, can only be positive.  In set notation we write this as,  

In words we say, "The range is y in the real numbers, such that y is greater than 0."

Next I worked out a word problem from you textbook which showed that the domain and range of a function can be restricted in a physical situation (ie. word problems).

For question 7 on page 64, the domain and range are

Because the rock falls from 80 meters to 0 meters in a time of 0 seconds to 4 seconds.

Homework

P. 63 # 1-12

(Hint: for many of these questions you might want to graph the equations.  Use your favourite graphing app or this online graphing calculator.)

Handout: More practice on the roles of a, h and k.