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messersmith_power_intermediate_algebra_1e_ch4_7_10

In 1998, 18,797 thousand tons of sulfur dioxide were released. Notice, the equation is in slope-intercept form, y mx b, and our result is b. That is because to fi nd the y-intercept, let x 0. To determine how much sulfur dioxide was released in 2004, let x 6 since 2004 is 6 years after 1998. y 1080.5(6) 18,797 Substitute x 6. y 6483 18,797 Multiply. y 12,314 In 2004, 12,314 thousand tons of sulfur dioxide were released into the air. Using Technology We can use a graphing calculator to explore what we have learned about perpendicular lines. 1) Graph the line y 2x 4. What is its slope? 2) Find the slope of the line perpendicular to the graph of y 2x 4. 3) Find the equation of the line perpendicular to y 2x 4 that passes through the point (6, 0). Express the equation in slope-intercept form. 4) Graph both the original equation and the equation of the perpendicular line: y 2x 4 5) Do the lines above appear to be perpendicular? 6) Press ZOOM and choose 5:ZSquare: 7) Do the graphs look perpendicular now? Because the viewing window on a graphing calculator is a rectangle, squaring the window will give a more accurate picture of the graphs of the equations. y x 1 2 y 2x ANSWERS TO YOU TRY EXERCISES 1) y 2 3 x 6 2) 5x y 2 3) 4x 3y 7 4) y 7 5) a) perpendicular b) neither c) parallel d) perpendicular 6) y 3 4 x 11 7) x 3y 21 ANSWERS TO TECHNOLOGY EXERCISES 1) 2 2) 1 2 3) y 1 2 x 3 5) No, because they do not meet at 90 angles. 7) Yes, because they meet at 90 angles. www.mhhe.com/messersmith SECTION 4.3 Writing an Equation of a Line 181


messersmith_power_intermediate_algebra_1e_ch4_7_10
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