1 Lesson 14, Section 2.5 (part 1) Begin with the slope formula. 1112121 xxyymxxyym−−=→−−= Cross multiply in this proportion. )(11xxmyy −=− This is known as the Point-Slope Form of a line equation. A Point-Slope Form Ex 1: Write an equation in point-slope form for these lines. a) slope is - ½ and point is (-2, 3) b) slope is 1112and point is (6, -12) Ex 2: Identify the slope and an indicated point for these lines. a) )1(732 +=− xy b) )21(68 −−=+ xy B Finding equations and graphing from point-slope form a) Find an equation of a line through (2, -3) with a slope of -3 and graph.2 b) Find an equation of a line through (-6, -1) with a slope of 23and graph. c) Find an equation of a line through points (2, 6) and (4, 1). d) Find an equation of a line through points (-3, 0) and (-7, 3).3 C Application Problems In 1971 the average American man consumed 2450 calories per day. By 2000, it increased to 2618/day. If this is a linear pattern and the number of calories per day is a near constant rate of change, represent the number of calories per day for the average American man in terms of t years after 1971. a) Write a function to represent this situation. Use your function to predict the following. b) number of calories the average American man will consume per day in 2008 c) what year the number of calories will reach
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