# 4.7 graphing lines using slope intercept form goal: graph lines in slope intercept form

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4.7 Graphing Lines Using Slope Intercept Form Goal: Graph lines in slope intercept form. Slide 2 Slope-Intercept Form of the Linear Equation y = mx + b m = slope b = y-intercept Any linear equation which is solved for y is in slope-intercept form. Slide 3 Find the slope and y-intercept of the following linear equations: y = 3x + 4 m = 3b = 4 y = - 2x - 1 m = - 2b = - 1 y = x - 94 m = b = 9 4 -2-2 1 -2-2 -1 y = 5x m = 5b = 0 Slide 4 Write a linear equation in the form y = mx + b given the following. m = 2, b = -3 m =, b = 5 y = 2x - 3 Slide 5 +3+3 +2+2 -3-3 Graph the following linear equation using slope and y-intercept. x y 1) Find the slope and y-intercept. Steps 2) Plot the y-intercept. m = 2 3 or m = -2-2 4) Draw line through points. 3) Plot the slope. -2-2 -3-3 Slide 6 +1+1 -3-3 Graph the line which passes through (-2, 1) and has a slope of -3 Graph the line which passes through (-2, 1) and has a slope of -3. x y 1) Plot the point. Steps 2) Write slope as fraction and count off other points. m = - 3 = -3-3 1 or m = 3 -1 3) Draw line through points. Slide 7 +4+4 +3+3 Graph the line which passes through (3, 2) and has a slope of. x y 1) Plot the point. Steps 2) Write slope as fraction and count off other points. m = 3 4 or m = -3-3 -4-4 3) Draw line through points. 3 4 Slide 8 Write a linear equation in slope-intercept form to describe each graph. y = mx + b x y x y b = 3 y = 2x + 3 b = -4 4 8 -6 2 Slide 9 Sometimes we must solve the equation for y before we can graph it. The constant, b = 3 is the y-intercept. The coefficient, m = -2 is the slope. Slide 10 1) Plot the y-intercept as a point on the y-axis. The constant, b = 3, so the y- intercept = 3. 2) Plot more points by counting the slope up the numerator (down if negative) and right the denominator. The coefficient, m = -2, so the slope = -2/1. right 1 down 2 right 1 down 2 Slide 11 Parallel Lines Graph the following on the coordinate plane. x y Parallel lines have the same slope. Slide 12 -3x Tell whether the lines below are parallel. 1) 3x + y = 7 y = -3x + 1 y = -3x + 7 m = -3 y = mx + b m = -3 Lines are parallel! Same slope!