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Pre-Calc w/Trig Problem of the Day Find the Slope and y-intercept of the following 4(y – 6) + 8y – 2x = 4(y – 5) Answer: y = ¼ x + ½ So m = ¼ and b = ½
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Pre-Calc w/Trig Lesson 1.4 B Objectives: SSBAT write the equation of a line given a point and the slope or 2 points on the line. SSBAT write the equation of a line parallel or perpendicular to a given line and given a point. Standards: M11.A.2.2.1, M11.D.2.1.3, M11.D.3.2.2
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Writing an Equation given the Slope and Y-intercept Substitute the slope and y-intercept into the equation y = mx + b for m and b
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2. Slope is -9 and y-intercept is -4 m b y = -9x – 4
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Point-Slope Form of the Equation of a Line Used to write the equation of a line given 1) A point on the line and the slope 2) 2 points on the line y - y 1 = m(x - x 1 ) Where m is the slope and (x 1, y 1 ) is a point on the line
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1. Find the equation of the line containing the point (1,-2) and having a slope of 3. Write your answer in slope- intercept form. y - (- 2) = 3(x - 1) y + 2 = 3x – 3 y = 3x – 5
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2. Find the equation of the line containing the point (-8, 5) and having a slope of ½. Write your answer in slope-intercept form. y - (5) = ½ (x - -8) y - 5 = ½ x + 4 y = ½ x + 9
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3.Find the equation of the line containing the points (8, -1) and (2, 5) Write your answer in slope-intercept form. 1 st find the slope of the line through the points 2 nd choose one point and use point-slope form
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Equation of Horizontal Line y = # Equation of Vertical Line x = # Remember: Horizontal Line Slope is 0 Vertical Line Slope is Undefined
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1. Write the equation of the line through the points (-3, 8) and (7, 8) Slope of 0 Horizontal Line Equation of Horizontal Line y = # The number is the y-coordinate of the point it goes through Equation of Line is y = 8
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2. Write the equation of the line through the points (5, 4) and (5, -7) Slope is UNDEFINED Vertical Line Equation of Vertical Line x = # The number is the x-coordinate of the point it goes through Equation of Line is x = 5
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On Your Own. Write the equation of each line. Write your answer in slope-intercept form. 1.Through the points (4, -1) and (1, 5) 2.Perpendicular to the line y = 5/2 x + 7 and through (-4, 0) y = -2x + 7
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No Homework
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Day 2 – In Class Page 40 – 41 #17 – 24 All #25, 27, 30 #36 – 41 All
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