Name: ________________________
ALGEBRA IB
Date: ____________
5-4 NOTES
Period:______
(continued):
Writing a Function Rule
Writing a Function Rule from a Situation
Don’t forget about DEPENDENT VARIABLE and INDEPENDENT VARIABLE!
“________________” depends on “________________”
Examples:
a) On Anna’s wall there is a painting of a rabbit. The rabbit in the painting
is 5 times the size of a normal rabbit. Write a function rule f(n) to
describe this relationship, where n represents the size of a normal rabbit.
b) Suppose you borrow money from a relative to buy a lawn mower that
costs $245. You charge $18 to mow a lawn. Write a rule f(m) to describe
your profit as a function of the number of lawns mowed, m.
c) Melanie gets paid $19 per hour. Write a rule f(h) to describe her income as
a function of the number of hours, h, she works.
You Try!!
1) Suppose you buy a word-processing software for $199. You charge $15
per hour for word-processing. Write a rule g(h) to describe your profit as
a function of the number of hours, h, you work.
2) Write a rule for the total cost t(p) for p ounces of peanuts if each ounce
costs $0.80.
Name: ________________________
ALGEBRA IB
Date: ____________
Period:______
More Practice…
1: A carpenter buys finishing nails by the pound. Each pound of nails costs
$1.20. Write a function rule C(p) to describe the cost of buying p pounds of
nails.
2: Suppose you borrow money from a relative to buy a lawn mower that costs
$245. You charge $18 to mow a lawn. Write a rule to describe your profit P(n)
as a function of the number of lawns mowed n.
3: Suppose you buy a word-processing software package for $199. You charge
$15 per hour for word processing. Write a rule to describe your profit P(h) as a
function of the number of hours you work h.
4: Write a function rule for the area A(l) of a square when you know the length
l of a side.