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2.4: Using Linear Models You can't choose the ways in which you'll be tested. 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. 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? Scatter Plots 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). Trend line: a line that approximates the relationship between the data sets of a scatter plot. Used to make predictions. Scatter Plots Graph the set of data. Decide whether a linear model is reasonable. If so, draw a trend line and write its equation by hand. Then use a graphing utility to determine the equation of the trend line. {(1, 2), (3, 3), (3, 3.75), (4, 4), (5, 3.25), (6, 4.5)} 2.4: Using Linear Models HW: 1-8 all, 13, 15, 16, 19, 21 You can't choose the ways in which you'll be tested.