Use point-slope form to write an equation EXAMPLE 3 Write an equation in point-slope form of the line shown.

Use point-slope form to write an equation EXAMPLE 3 SOLUTION STEP 1 = y 2 – y 1 x 2 – x 1 m = 3 – 1 –1 – 1 = 2 –2 = –1 Find the slope of the line.

Use point-slope form to write an equation EXAMPLE 3 Method 1 Method 2 Use (–1, 3). Use (1, 1). y – y 1 = m(x – x 1 ) y – 3 = –(x +1)y – 1 = –(x – 1) STEP 2 Write the equation in point-slope form. You can use either given point. CHECK Check that the equations are equivalent by writing them in slope-intercept form. y – 3 = –x – 1 y = –x + 2 y – 1 = –x + 1 y = –x + 2

Use point-slope form to write an equation EXAMPLE 3 GUIDED PRACTICE for Example 3 Write an equation in point-slope form of the line that passes through the points (2, 3) and (4, 4). 3. y – 3 = (x – 2) or 1 2 y – 4 = (x – 4) 1 2 ANSWER