# Lesson 5.6 Point-Slope Form of the Equation of a Line.

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Lesson 5.6 Point-Slope Form of the Equation of a Line

Point-Slope Form of the Equation of a Line A line that passes through the point (x 1, y 1 ) with a slope of m. The point-slope form of the equation of the line is: y – y 1 = m(x – x 1 ) There is a difference between (x 1, y 1 ) and (x, y). –(x 1, y 1 ) is a specific point on the line. –(x, y) represents ANY point on a line.

A line is passing through the points (-3, 6) and (1, -2). Write the equation of a line in Point-Slope Form. Step 1: Find the slope. m = y 2 -y 1 = -2 – 6 = -8 = -2 x 2 -x 1 1 – - 3 4 Step 2: Substitute one point, (-3, 6) and the slope into the Point-Slope Form equation: y – y 1 = m(x – x 1 ) y – 6 = -2(x - - 3) y – 6 = -2(x + 3)

Change from Point-Slope Form to Slope-Intercept Form Write an equation of the line that passes through (2, 3) with a slope of – ½. Substitute into Point-Slope Form. y – y 1 = m(x – x 1 ) y – 3 = - ½(x – 2) Simplify the equation to put it into slope- intercept form. y – 3 = - ½x + 1 y = - ½x + 4

Which equation would you use? Slope-Intercept, Standard, or Point-Slope Form The line passes through the points (1, 3) and (-2, 4). Point-slope because a point is given and a slope can be determined. The line has a slope of -4 and has a y- intercept of -12. Slope-intercept form because a slope and the y-intercept are given.

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