2-4: Writing Linear Equations Using Slope Intercept Form

Writing Linear Equations To write a linear equations, there are two things that you will need. Slope and Y- intercept We will substitute this information into the following equation.

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 from a graph 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 = 0x+4 y=4 x y

Find the Slope and y-intercept of each Equation: 1) y = -4x + 3 m = -4 b = 3 2) y = 5 - x m = - b = 5 3) 8x + y = m = -8 b = 4) 4x - 2y = 10 m = 2 b = -5

Find the Equation Given the Slope and y-intercept 1) m = -3, b = 1 y = -3x + 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 = mx + b 1 = -1(2) + b 1 = -2 + b 3 = b

continue Using the information just found, substitute it into the slope intercept formula. y = mx + b y = (-1)x + (3)

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

Find the Equation Given a Point and a slope Another method that can be used to generate an equation of a line from a point and a slope is the point-slope formula. y – y1 = m(x – x1)

Find the Equation Given Two Points Given m = -5 and the point (7,1).Write an equation of a line using the point-slope formula. y – 1 = -5(x – 7) y – 1 = -5x + 35 + 1 + 1 y = -5x + 36