2.5 1
Section 2.5Other Equations of Lines
Point-Slope Form (y – y1)=m(x – x1) Special pairs of lines:
Parallel Lines m1 = m2
Perpendicular lines m1 = -1 / m2
2.5 2
Point-Slope Form of a Line Slope-Intercept Form y = mx + b
Given an equation, it’s easy to find its slope and y-intercept, and graph it Standard Form Ax + By = C
Given an equation, it’s easy to find both intercepts, using them to graph it Point-Slope Form (y – y1) = m(x – x1)
Given a slope and any point, it’s easy to write a line’s equation
2.5 3
Writing a Line’s Graph using the slope and any one point (x1,y1)
Was this stepReally Necessary?
(3,4)(5,3)
2.5 4
Writing an Equation in Function Form (slope/intercept):What if all we know are 2 points on a line?
2.5 5
Application
2.5 6
Slopes of Parallel Lines m1 = m2
But wait! How can you be sure that it’s not the same line ?
AND differenty-intercepts!
2.5 7
Slopes of Perpendicular Lines m1 = -1 / m2
2.5 8
Slopes of Perpendicular Lines m1 = -1 / m2
2.5 9
Overview - 2.6 The Algebra of Functions