2­4.notebook
September 22, 2011
Algebra II
9/20/10
Pg. 74: #18
Pg. 77: #2 and #8
Sep 19­8:33 AM
Algebra II: Section 2.4
Writing linear equations that model real world data
Making predictions from linear models
An airplane descends at a rate of 300 ft/min from an
elevation of 8000 feet. 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.
Sep 19­8:47 AM
A spring has a length of 8 cm when a 20-g mass hangs at the
bottom end. Each additional gram stretches the spring
another 0.15 cm. Write an equation to model the length of y
of the spring as a function of the mass x of the attached
weight. Graph your equation and interpret the meaning of
the vertical intercept.
Sep 22­7:12 AM
Sep 19­8:51 AM
A candle is 6 inches tall after burning for an hour.
After 3 hours, it is 5 1/2 inches tall. Write a linear
equation to model the height y of the candle after
burning x hours
In how many hours will the candle be 4 inches tall?
Sep 22­7:13 AM
Sep 19­8:53 AM
1
2­4.notebook
September 22, 2011
Graphs that relate two different sets of data by plotting the data as ordered pairs. Used to determine the relationship between data sets (for example, x and y values).
In how many hours will the candle be 4 inches tall?
Trend line: a line that approximates the relationship between the data sets of a scatter plot. Used to make predictions.
Sep 22­7:15 AM
Sep 16­7:32 AM
An art expert visited a gallery and jotted down her guesses for
the selling price of five different paintings. Then, she checked
the actual prices. That data points (guess, actual) show the
results, where each number is in thousands of dollars.
(12, 11) (7, 8.5) (10, 12) (5, 3.8) (9, 10)
A. Draw a scatter plot. Decide whether a linear model is
reasonable.
B. Draw a trend line if it is reasonable and find the equation of
the line.
Sep 22­7:25 AM
Sep 19­9:01 AM
Homework
Pg. 81 - 83: 1, 3, 5, 8, 9, 12, 15,16, 26
Sep 22­7:16 AM
Sep 19­9:02 AM
2