Section 2-4: Writing Linear Equations

1
Section 2-4 Writing Linear Equations

• We have already seen standard form of an
  equation, but this form isnt very useful.
• We are going to use slope-int. and point-slope
  form to write equations.

2
Slope-Intercept Form

• y ______ ____ mx b
• Remember, MOST of the time we will still have
  ______ in the final equation.
• m is the _______
• b is the __________

3
Write the equation of the line.

• First (and easiest) b ?
• b
• m ?
• m
• y

4
Write the equation of the line.

• b ?
• b
• m ?
• m
• y

5
Write the equation of the line.

• b ?
• b
• m ?
• m
• y

6
Give the slope and y-int. of each equation.

• y -4x 3
• m
• b
• y 5 - 1/2x
• m
• b

• 8x y 3/4
• m
• b
• 4x - 2y 10
• m
• b

7
Give the slope and y-intercept of each line.

• y -1/3x
• m
• b

• y 5
• m
• b

8
Given the slope and y-int., write the equation
of the line.

• m 0, b 10
• m 1, b 0
• m 0, b 0

• m -3, b 1
• m -2/5, b -4

9
Given the graph, write the equation of the line.

• To write the equation of a line, we need two
  pieces of information ___________
  ________________
• You should be able to get these from _________.

10
Point-Slope Form

• Use this form if you are given _________, or a
  __________. (as long as the pt. isnt b)
• ____________________
• (x1, y1) is one of the given points.
• Use the points to calculate m.

11
Give the equation of the line.

• the line goes through (3, 2) (5, 4).
• m
• choose either point, well use (3, 2). Plug in 3
  for ___ 2 for ____.
• ____________

12
Write the equation.

• y - 2 1(x - 3)
• Simplify.
• ______________
• add two to both sides
• __________

13
Give the equation of the line through the points
(4, 3) and (7, -2)

• m
• plug either point.
• y - 3
• y
• y

14
Give the equation of the line with x-int. 3 and
y-int 2.

• Because we know the y-int. (b), we only need the
  slope.
• m
• y