4.4 21st feb 2013
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Transcript of 4.4 21st feb 2013
4.4 Notes.notebook
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February 21, 2013
Mar 201:53 PM
4.4 Restrictions on Composite Functions
If the domain of 2 functions is then the domain of their composition will be the sameand have no restrictions.
Ex) Look at f(x)=2x1 g(x)=x21 and f(g(x)).
Notice that the LEFT screen has been set so that onlythe composite function is displayed.What is the equation of f(g(x))? Notice its domain?
__________________What is the range of f(x), of g(x)?How would we find the range of f(g(x))?
4.4 Notes.notebook
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February 21, 2013
Mar 202:04 PM
Use the same 2 equations to find the equation for g(g(x))Again, notice its domain is ALL inclusive.
Use your calculator to find the range of this function.Your screen should look like this:
4.4 Notes.notebook
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February 21, 2013
Mar 202:08 PM
So far we conclude that if the domains of functions areall inclusive, so is the domain of their composite.
The range is more difficult to determine and might requirethe help of a calculator.
What if the domains of the original functions are NOT allinclusive. What about the composite function's domain??
4.4 Notes.notebook
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February 21, 2013
Mar 202:10 PM
If and g(x) = x+3
state the domain of both f(x) and g(x) and find the domainof:
1) f(g(x)) Hint: Find the composite function and then determineits domain.
2) g(f(x))
4.4 Notes.notebook
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February 21, 2013
Mar 202:17 PM
Remember, domains are restricted by NonPermissible Values. Denominators must NOT equal 0.
4.4 Notes.notebook
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February 21, 2013
Mar 202:17 PM
4.4 Notes.notebook
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February 21, 2013
Mar 202:19 PM
In this case, compose the function and then remember that Square Root functions only exist for positive values. This will determine the restrictions on the domain.
4.4 Notes.notebook
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February 21, 2013
Mar 202:19 PM
Now try these:
This one has issues! The square root disappears inthe composition, but since the domain of f(x) is restricted,so is the domain of g(f(x)). Be careful.
4.4 Notes.notebook
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February 21, 2013
Mar 202:14 PM
Now let's get creative.The final type of question GIVES the composite functionand asks for the original functions that would produce thiscomposition. Obviously in many cases, more than one answerwill work.
4.4 Notes.notebook
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February 21, 2013
Mar 203:25 PM
a) g(x) = _________
f(x) = _________
Does your f(g(x) work?
b) g(x) = ___________
f(x) = ____________
4.4 Notes.notebook
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February 21, 2013
Mar 203:25 PM
4.4 Notes.notebook
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February 21, 2013
Mar 202:15 PM
Homework: Page 314 #3, 4(use calc. for range), 5(in class), #6a)b)c) [d for challenge]7a)c), 9a)b), 10, 11a)b), 12, 14a) challengeMult. Choice #1,2.Supplementary 3 Handout