2.4: Using Linear Models
Objective: Use linear equations
to solve real world models.
Writing Equations
Ex1) Suppose an airplane descends at a rate of 300 ft/min from an
elevation of 8000 ft. Write and graph an equation to model the plane’s
elevation as a function of the time it has been descending. Interpret the
intercept at which the graph intersects the vertical axis.
What is a reasonable domain and range? Why?
What do you already know?
Brainstorm ways to solve the problem
What do you
need to find?
Try it here
Explanations you
need to include.
Using Points
A spring has a length of 8 cm when a 20-g mass is hanging at the bottom
end. The same spring has a length of 11 cm when a 40-g mass is hanging
at the bottom end. Write an equation for the length y of the spring as a
function of the mass x of the attached weight. Graph the equation. What
mass would be needed to stretch the spring to a length of 12 cm?
What is a reasonable domain and range? Why?
What do you already know?
Brainstorm ways to solve the problem
What do you
need to find?
Try it here
Explanations you
need to include.
Writing Equations
Ex3) Jacksonville, FL has an elevation of 12 ft above sea level. A hot-air
balloon taking off from Jacksonville rises 50 ft/min. Write an graph an
equation to model the situation. Interpret the intercept at which the graph
intersects the vertical axis.
What is a reasonable domain and range? Why?
Writing Equations
Ex4) Your power went out and all you have is a candle to see. The candle
is 6 in tall after burning for 1 hr. After 3 hrs it is 5 ½ in tall. Write and
graph an equation to model the situation (no decimals).
After how many hours are you going to need to light a new candle?
What is a reasonable domain and range? Why?
2.4: Using Linear Models
Homework #13:
Pg 81 #1-7
2.1 – 2.4 QUIZ FRIDAY!!