Presentation on theme: "2.4 Write Equations of Lines"— Presentation transcript:
12.4 Write Equations of Lines Date: 9/4Objective: Use point slope formula to write and equation of a line.
2Slope Intercept Form: y = mx + b Point Slope Formula:y – y1 = m(x – x1)If Given a slope m and a point (x1 , y1 ), then usepoint slope formula to write an equation of aline that passes through the point using that slope.If Given (x1 , y1) and (x2 , y2 ) then you must find the slope first using the slope formula, then use the point slope formula to write the equation of the line.
3Example: Write an equation when given the slope and y-intercept. m = ¾ b = -2
4Write an equation when given the slope and a point. Write an equation of a line that passes through (5,4) and has a slope of -3.
5Write an equation of a line when given two points. Write an equation of a line that passes through the points (5,-2) and (2,10).1st: Use slope formula to find (m = )2nd: Use point slope formula
6Write equations of parallel or perpendicular lines. Write an equation of the line that passes through (-2,3) and is (a) parallel to and (b) perpendicular to, the line y = -4x + 1.