Writing Linear Equations: Slope-Intercept Form, Parallel & Perpendicular Lines
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In this lesson on writing linear equations, you'll learn how to write equations in slope-intercept form given the slope and y-intercept, a point with the slope, or two points. We’ll cover writing equations for parallel and perpendicular lines, using the formula ( y = mx + b ), where ( m ) is the slope and ( b ) is the y-intercept. You'll practice finding equations of lines that pass through given points, as well as explore the characteristics of parallel and perpendicular lines. Solutions will be provided for practice exercises.
Writing Linear Equations: Slope-Intercept Form, Parallel & Perpendicular Lines
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Presentation Transcript
Chapter 2.4 Writing Linear Equations
By the end of this lesson you will be able to: • Write an equation in slope-intercept form when given: slope and a y-intercept a point and the slope two points • Write an equation of a parallel line • Write an equation of a perpendicular line
Slope-Intercept Form: Y = mx + b B = y-intercept M = slope of the line
Writing equations of Lines: • Given slope of -8 and passes through (2,4) • Take the equation y=mx+b and substitute the -8 in for “m” • Y = (-8)x + b • To find the value of “b” – take the value of x and y from the point and substitute • (4) = (-8)(2) +b • b = 20 • Y = -8x + 20
You Try! • Write the equation of the line with a slope of 3 and passing through (0, -5).
Equations – given two points: • Given two points (4,1) and (7,7) • Find the slope using the slope formula • Plug 2 in for “m” • Pick one of the points to get the values for the x and y • Once you get the value for “b” then rewrite the equation • Y = 2x - 7 (1) = (2)(4) + b b = -7
You Try! • Write the equation of the line that passes through the points (4, 8) and (-2, 10).
Parallel Lines: • Parallel Lines have the same slope • Write an equation that is parallel to y=3x+2 and passes through (0,2) • The new line would have the same slope, so m=3 • Take the x and y from the point and find “b”
You Try! • Write an equation that is parallel to y=1/2x + 4 and passes through (-8, 3)
Perpendicular Lines: • Perpendicular Lines have slopes that are opposite-reciprocal • Write an equation that is perpendicular to y= -½x +2 and passes through (8,2) • The new line’s slope would be 2 • Take the x and y value to find b • Then rewrite the new equation
You Try! • Write and equation that is perpendicular to y = - 1/3x – 4 and passes through (2, 5)
Tonight’s Homework: Page 79 (23-37 odd)