Presentation on theme: "Writing an Equation of a Line"— Presentation transcript:
1Writing an Equation of a Line Determine the equation of a line and/or graph a linear equation.
2Slope-intercept Form y = mx + b any ordered pair (x,y)Slope-intercept Form y = mx + bSlope y-intercept
3The method used to write an equation of a line depends on the information aboutthe line that is available.
4If given the slope and y-intercept, slope-intercept form.Examplem = 5, b = 757y = ___ x + ___
5If given a point and the slope, Examplem = –2, contains (5, –8)Step 1Substitute –2 for m, 5 for x, and–8 for y; then simplify to findthe value of b.y = mx + b–8 = –2(5) + b–8 = –10 + b2 = bStep 2Substitute –2 for m, and 2 for b.y = –2x + 2
6If given two points, First, find the slope using the slope formula. Examplecontains (5, –8) and (2, 7)m = 15–3m = –5m = 7 – -82 – 5
7If given two points, continued Then use the slope you just found and EITHERpoint to work like the previous example.y = -5x + b7 = -5 (2) +b7 = b17 = bm = –5,contains (5, –8) and (2, 7)y = –5x + 17
9you try Find the equation of each line using the given information. m=2, y-intercept is -1the line passes through the points (8, 2) and (12, 4)the line is parallel to the line y = ⅔x + 4, and passes through the points (6, 7)