Presentation on theme: "3.7 Equations of Lines in the Coordinate Plane"— Presentation transcript:
13.7 Equations of Lines in the Coordinate Plane The slope m of a line is the ratio `of the vertical change (rise) to the horizontal change (run) between any two points.
2Find Slopes of LinesFind the slope of line a and line d.
3Slopes of Lines in Coordinate Planes Negative slope – falls from left to right.Positive slope – rises from left to right.Zero slope (slope of 0) – horizontal lineUndefined slope – vertical line
4Forms of Linear Equations The slope intercept form of an equation of a nonvertical line is y = mx + b, where m is the slope and b is the y-intercept.The point-slope form of an equation of a nonvertical line is y – y1 = m (x – x1), where m is the slope and (x1 , y1) is a point on the line.
5Graphing LinesWhat is the graph ofStarting point (0 , 1)
6Graphing Lines What is the graph of y – 3 = -2 (x + 3) Starting point (-3 , 3)
7Writing Equations of Lines What is an equation of the line with the slope 3 and y – intercept -5?y = mx + by = 3x – 5
8Writing Equations of Lines What is the equation of the line through point (-1 , 5) with slope 2?y – y1 = m (x – x1)
9Using Two Points to Write an Equation What is an equation of the line with points (-2 , -1) and (3 , 5)?
10Writing Equations of Horizontal and Vertical Lines What are the equations for the horizontal and vertical lines through (2 , 4)?y = 4 – horizontal linex = 2 – vertical line