Advanced Algebra Notes Section 2.4: Write Equations of Lines Given slope and y-intercept b Use slope-intercept form = + Given slope and a point (, ) Use point slope form − 1 = − 1 Given points (1 , 1 ) and (2 , 2 ) First use the slope formula to find m. ℎ ! Then use point-slope form with either point () () = ℎ ℎ ! () Example 1 Write an equation of the line shown. = + ℎ ? ℎ ℎ ℎ ℎ − ? 3 = + (−2) 4 Example 2 Write an equation of the line that passes through (5,4) and has a slope of −3. − 1 = ( − 1 ) − ℎ ! − 4 = −3( − 5) − 4 = −3( − 5) − 4 = −3 + 15 = −3 + 19 Example 3 Write an equation of the line that passes through (−2,3) and is Parallel to the line = −4 + 1 ℎ ℎ ℎ ! = −4 + −5 = = −4 − 5 3 = −4(−2) + Perpendicular to the line = −4 + 1 ℎ ℎ ! 1 1 − 1 = −4( − 1 ) 1 7 = + +3 = + 1 4 2 4 2 − 3 = ( + 2) 4 Example 4 Write an equation of the line that passes through (5, −2) and (2,10) ℎ ! 10 − (−2) = 2−5 12 = −3 = −4 ℎ ! − 1 = −4( − 1 ) ℎ ! − (−2) = −4( − 5) + 2 = −4 + 20 = −4 + 18 Example 5 In the school year ending in 1993, 2.00 million females participated in U.S. high school sports. By 2003, the number had increased to 2.86 million. Write a linear equation that models female sports participation. = # = # = + = (.086) + ℎ ℎ ℎ 1993 2003 … ℎ … ℎ ! 2.86 − 2.00 = 10 − 0 = .086 2.00 ℎ = (.086) + 2.00 Closing: How do you write an equation of a line? ℎ , − ℎ ℎℎ … − = + − − 1 = ( − 1 ) HOMEWORK #1 − 19

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# 2.4 Notes