2.5 Linear Equations

1
2.5 Linear Equations
2

• Graphing using table
• Graphing using slope and y-intercept (section
  2.4)
• Graphing using x-intercept and y-intercept
  (section 2.5)

X-intercept
y-intercept
3

• To find x-intercept, set y 0, solve for x
• To find y-intercept, set x o, solve for y
• Ex1) 3x 2y 12

4

• Ex2) y -4x 5
• Ex3) x (1/2)y -8

5

• To graph a linear equation, find x-intercept and
  y-intercept, plot them then connect the points.
• Ex y 2x - 4, we have x-intercept (2, 0)
• 
  y-intercept (0, -4)

(2,0)
(0,-4))
6

• Standard Form of Linear Equation
• Ax By C
• Slope-Intercept Form
• y mx b
• Point-Slope Form
• y y1 m (x x1)

7

• Two lines are parallel if they have the same
  slope
• Ex y 3x 4
• y 3x - 2
• Two lines are perpendicular if the product of
  their slopes -1 (or one slope is the opposite
  reciprocal of the other slope).
• Ex y (1/3) x
• y -3x - 2

8

• Are these lines parallel, perpendicular, or
• neither?
• y (-3/2)x 4
• 2y 3x 1
• y 5x
• 5y 15 x
• 3) x 3y 3
• 3x 1 y

9

• Horizontal line
• slope 0
• Ex y 4 or y -2
• Vertical line
• slope is undefined
• Ex x 4 or x -2