Writing Linear Equations Using Slope Intercept Form  Point-Slope Form.
 
We’ve learned to graph  given an equation. Now we’ll learn to write the equation given the graph There are three ways. It all depends on what information you are given as to which process you use.
Slope-Intercept Form y  =  mx  +  b   [or  f ( x ) =  mx  +  b ] m  is the slope b  is the  y -intercept
Find the Equation of the Line   What is the  y -intercept? b  = -2 What is  m ? m  =  y  =  x  -2 x y
Find the Equation of the Line b  = ? b  = 1 m  = ? m  =  - y  =  -   x  + 1 x y
Find the Equation of the Line b  = ? b  = 4 m  = ? m  = 0  y  = 0 x + 4 y =4 x y
Find the Slope and y-intercept of each Equation: 1)  y  = -4 x  + 3 m  = -4 b  = 3 2)  y  = 5 -  x m  =  - b  = 5 3) 8 x  +  y  =  m  = -8 b  =  4) 4 x  - 2 y  = 10 m  = 2 b  = -5
Find the Equation Given the Slope and  y -intercept 1)  m  = -3,  b  = 1 y  = -3 x  + 1 2)  m  = -   ,  b  = -4 y  = -  x  - 4
Find the Equation Given the Slope and a Point Given  m  = -1, (2, 1) First, calculate  b  by substituting the slope and the coordinates into  y  =  mx  +  b. y  = -1 x  +  b 1 = -1(2) +  b 1 = -2 +  b 3 =  b y  = -1 x  + 3
If you are given two points on the line Find the slope using the two points Then plug this slope and either  one  of the points into the point slope formula.
Find the Equation Given Two Points Given (-1, 3) and (2, 1) First, calculate the slope:    Second, find  b .  Use  either point... m  =  ,  (2, 1) 1 =  (2) +  b 1 =  +  b     = b
Use Point Slope Form: If you are given slope, m, and a point (x 1 ,y 1 ) on the line y – y 1  = m ( x – x 1 )
Write an equation of a line containing the point (1,2) with slope of -1/2. Use (x 1 ,y 1 ) = (1,2) & m = -1/2 y – 2 = -1/2 ( x – 1) Now you can simplify to the slope intercept form y – 2 = -1/2 x + ½ y = -1/2 x + 5/2
Given two points (-2,2) & (3,7) Find the slope:  m=1 Plug this slope and one of the points into the point slope formula. y – 2 = 1 ( x – (-2)) y – 2 = x + 2 y = x + 4  (put the equation into slope intercept form) (-2,2) (3,7)

Writing linear equations

  • 1.
    Writing Linear EquationsUsing Slope Intercept Form Point-Slope Form.
  • 2.
  • 3.
    We’ve learned tograph given an equation. Now we’ll learn to write the equation given the graph There are three ways. It all depends on what information you are given as to which process you use.
  • 4.
    Slope-Intercept Form y = mx + b [or f ( x ) = mx + b ] m is the slope b is the y -intercept
  • 5.
    Find the Equationof the Line What is the y -intercept? b = -2 What is m ? m = y = x -2 x y
  • 6.
    Find the Equationof the Line b = ? b = 1 m = ? m = - y = - x + 1 x y
  • 7.
    Find the Equationof the Line b = ? b = 4 m = ? m = 0 y = 0 x + 4 y =4 x y
  • 8.
    Find the Slopeand y-intercept of each Equation: 1) y = -4 x + 3 m = -4 b = 3 2) y = 5 - x m = - b = 5 3) 8 x + y = m = -8 b = 4) 4 x - 2 y = 10 m = 2 b = -5
  • 9.
    Find the EquationGiven the Slope and y -intercept 1) m = -3, b = 1 y = -3 x + 1 2) m = - , b = -4 y = - x - 4
  • 10.
    Find the EquationGiven the Slope and a Point Given m = -1, (2, 1) First, calculate b by substituting the slope and the coordinates into y = mx + b. y = -1 x + b 1 = -1(2) + b 1 = -2 + b 3 = b y = -1 x + 3
  • 11.
    If you aregiven two points on the line Find the slope using the two points Then plug this slope and either one of the points into the point slope formula.
  • 12.
    Find the EquationGiven Two Points Given (-1, 3) and (2, 1) First, calculate the slope: Second, find b . Use either point... m = , (2, 1) 1 = (2) + b 1 = + b = b
  • 13.
    Use Point SlopeForm: If you are given slope, m, and a point (x 1 ,y 1 ) on the line y – y 1 = m ( x – x 1 )
  • 14.
    Write an equationof a line containing the point (1,2) with slope of -1/2. Use (x 1 ,y 1 ) = (1,2) & m = -1/2 y – 2 = -1/2 ( x – 1) Now you can simplify to the slope intercept form y – 2 = -1/2 x + ½ y = -1/2 x + 5/2
  • 15.
    Given two points(-2,2) & (3,7) Find the slope: m=1 Plug this slope and one of the points into the point slope formula. y – 2 = 1 ( x – (-2)) y – 2 = x + 2 y = x + 4 (put the equation into slope intercept form) (-2,2) (3,7)