4-1 Usin g Gr ap h s t o Rel at e Tw o Qu an t i t i es
Quick Review
You can use graphs to represent th e relationship betw een
two variables.
— ------------ A
Ex a m p l e
A dog owner plays fetch with her dog. Sketch a graph to
represent the distance between them and the time.
Playing Fetch1
Ex e r c i se s- Travel A c a r’s speed increases as it m erges onto a
highway. The car travels at 65 m i/h on th e highway
until it slows to exit. The car th e n stops at three traffic
lights before reaching its destination. Draw a sketch
of a graph th a t shows th e car’s speed over time. Label
each section. - Surfing A professional surfer paddles out past
breaking waves, rides a wave, paddles back out past
th e breaking waves, rides a n o th er wave, an d paddles
back to th e beach. Draw a sketch of a graph th at
shows the surfer’s possible distance from th e beach
over time.
4-2 Patterns and Linear Functions
Quick Review
A function is a relationship th at pairs each in p u t value
with exactly one output value. A linear fu n ctio n is a
function w hose graph is a line or p a rt of a line.Ex a m p l e
The number y of eggs left in a dozen depends on the
number x of 2-egg omelets you make, as shown in
the table. Represent this relationship using words, an
equation, and a graph.
r
Number of Omelets Made, x
JL(^12) 3 1
Number of Eggs Left, y
....^121086
Look for a pattern in the table.
Each time x increases by 1, y
decreases by 2. The num ber y of
eggs left is 12 m inus the quantity
2 t i m e s t h e n u m b e r x o f o m e l e t s
made: y= 12 — 2x.
12'
10
8
6
4
2
0
0 1 2 3 4 5 6 7
Ex e r c i s e s
For each table, identify the independent and dependent
variables. Represent the relationship using words, an
equation, and a graph.
Paint in Can Game Cost
Elevation
Number of Flights of
Stairs Climbed, n^012
hi
Elevation (ft above sea level), E 311 3 2 6^341356
284 Ch ap t er 4 Ch ap t er Review