POSSIBLE APPROACHES
CLASS QUESTIONS
- Can you think of functions for which this sort of approach
might not work?
- Does this method tell us anything about the number of roots
of an equation?
CONCEPT NOTES
- This is a quick problem in which students should be
encouraged to try out function evaluation for various choices
of numbers. Remember, that the key point is whether the
function is positive or negative: we don't need to evaluate the
exact values.
- For interested students you might wish to say that at
university this sort of idea is extended in courses on
Analysis, and this result is called the Intermediate Value
Theorem. It is actually a very useful and powerful mathematical
idea.
PROCESS NOTES
This problem suggests trial and error
CONTENT NOTES
EXTENSIONS
For example: it is easy to see that
(1+72x5)2-1is positive for x=1,
Interesting discussion questions / points are:
PROCESS
CONTENT