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CA Standards 7.0: Students verify that a point lies on a line, given and equation of a line. Students are able to derive linear equations by using that point-slope formula.
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CA Standards 7.0: Students verify that a point lies on a line, given and equation of a line. Students are able to derive linear equations by using that point-slope formula. Objective: Given a slope and a point, students will be able to write an equation of a line using the slope-intercept equation. Agenda for 10/19/11 1.) Warm-up 2.) Answers to yesterday’s assignment 3.) Lesson: Write an equation of a line given a slope and a point 4.) Class/Homework 5.) Stay On Task!!!
Point Slope Ex 1: What is the Slope-Intercept Form of the equation of the line containing the point (3,6) and having a slope of 4? • What do we know? Use y=mx+b • Slope (m): m = 4 So if y=mx+b Then6=4●3+b b = -6 • Y-intercept (b): Not yet 6=12+b • (3, 6) means • x = 3 and y = 6 -12 -12 -6=b Thus y=4x–6
Point Slope Ex 2: What is the Slope-Intercept Form of the equation of the line containing the point (1,7) and having a slope of -1? • What do we know? Use y=mx+b • Slope (m): m = -1 So if y=mx+b Then7=-1●1+b b = 8 • Y-intercept (b): Not yet 7=– 1 +b • (1, 7) means • x = 1 and y = 7 +1 +1 8=b Thus y=- x+8 1
Point Slope You try: What is the Slope-Intercept Form of the equation of the line containing the point (4,-5) and having a slope of -2? • What do we know? Use y=mx+b • Slope (m): m = -2 So if y=mx+b Then-5=-2●4+b b = 3 • Y-intercept (b): Not yet -5=-8+b • (4, -5) means • x = 4 and y = -5 +8 +8 3=b Thus y=-2x+3
Given Two Points Ex 3) What is the slope-intercept form of the equation of the line containing the points (3,2) and (1,-2) ? Use y=mx+b • What do we know? m = 2 • Slope (m): Not yet So if y=mx+b – -4 2 -2 = = Then2=2●3+b 1 -2 3 – = 2 2=6+b b = -4 • Y-intercept (b): Not yet -6 -6 • (3, 2) means • x = 3 and y = 2 -4=b Thus y=2x–4
Given Two Points Ex 4) What is the slope-intercept form of the equation of the line containing the points (6,-4) and (1, 1) ? Use y=mx+b • What do we know? m = -1 • Slope (m): Not yet So if y=mx+b – 5 -4 1 = = Then1=-1●1+b 1 -5 6 – = -1 1=-1+b +1 b = 2 +1 • Y-intercept (b): Not yet • (1, 1) means • x = 1 and y = 1 2=b Thus y=x+2 -1 –
3 m = 2 3 3 2 2 Given Two Points You try: What is the slope-intercept form of the equation of the line containing the points (4,5) and (2,2) ? Use y=mx+b • What do we know? • Slope (m): Not yet So if y=mx+b – -3 5 2 = = Then2=●2+b 2 -2 4 – 3 = 2=3+b 2 -3 -3 b = -1 • Y-intercept (b): Not yet -1=b • (2, 2) means • x = 2 and y = 2 Thus y= x-1
1 = – 2 1 1 Then2=●2+b – – 2 2 Thus y=x+3 Ex 5: Write an equation of the line that contains the two points graphed below. y Use y=mx+b (-2,4) • What do we know? -2 -2 (2,2) • Slope (m): m = 4 4 • Y-intercept (b): Not yet x • (2, 2) means • x = 2 and y = 2 So if y=mx+b 2=-1+b +1 +1 3=b
You Try: Write an equation of the line that contains the two points graphed below. y Use y=mx+b +2 • What do we know? (1,4) 6 • Slope (m): m = 3 = 2 +6 • Y-intercept (b): Not yet x • (1, 4) means • x = 1 and y = 4 (-1,-2) So if y=mx+b Then4=3●1+b 4=3+b -3 -3 Thus y=3x+1 1=b