Warm up
What is slope intercept form?
What are parallel lines?
What is point slope form?
What is standard form?
Slope Intercept Form of a line
 The linear equation y = mx + b is written in slope-
intercept form, where m is the slope and b is the yintercept
Y=mx + b
 Slope = m
 Y-intercept = b
Find the Slope and y-intercept of the
following equations in slope intercept
form
 Y= 4x + 7
 Y= 6x -3
 Y= -4x +3
Graph
Graph the
equation
• Y = -3x + 2
Parallel lines
 What are parallel lines?
 How would you draw them?
 What kind of slopes would they have?
 What kind of y intercepts would they have?
Parallel Lines
 Parallel lines are different lines in the same plane that never
intersect. Two lines are parallel if they have the same _____
and different ______________.
Parallel lines
 What would the slope and y-intercept have to be
for a line to parallel to the following lines.
 y = 4x – 5
 y = -2x + 3
Parallel lines
 Which of the following lines are parallel?
 y = 2x + 3
 y = -2x + 3
 y = 2x -2
 Which of the following lines are parallel?
 y = 4x + 5
 y = -3x + 5
 y = -3x + 4
Graph the lines how do you know for
certain if the lines are parallel?
Graph the equation
• Y = -3x + 2
• Y = -3x -3
Graph the lines how do you know for
certain if the lines are parallel?
Graph the equation
• Y = 2x + 3
• Y = 2x -4
Parallel lines
 Which of the following lines are parallel?
 3y = -9x -5
 2y – 6x = -5
 12x + 4y = 1
 Which of the following lines are parallel?
 3x + 2y =6
 3x -2y = 6
 6x + 4y = 6
Parallel Lines
 What kind of slopes do parallel lines have?
 What kind of y-intercepts do parallel lines have?
 Why do parallel lines have the same slope?
 Why do parallel lines have different y-
intercepts?
Perpendicular lines
 What are perpendicular lines?
 How would you draw them?
 What kinds of slopes would
perpendicular lines have?
Perpendicular lines
 Two lines in a plane are perpendicular if their slopes
are ___________ ___________. Their y-intercepts
can be the same or different.
 opposite (flip the sign)
1 1
2 2
3,3......  4,4....... , .......
,
10 10
3 3
 reciprocal (flip the fraction)
2 1
3 5
2 3
1
, ....... , ....... , ....... ,4
1 2
5 3
3 2
4
Perpendicular lines
 What would the slope need to be for a line to
be perpendicular to the following lines?
 y = ½x + 3
 y = -3x -2
Perpendicular lines
 What would the slope need to be for a line
to be perpendicular to the following lines?
 y = -⅔x + 7
 y = 6x -4
Perpendicular lines
 Determine whether the lies are
perpendicular
 y = 3x + 2
 y = -3x -1
 y = ⅕x - 4
 y = -5x + 3
Perpendicular lines
Determine whether the lies are perpendicular
 y = 2x + 3
 y = 2x -1
 y = ⅛x - 2
 y = -8x + 1
Graph the lines how do you know for
certain if the lines are perpendicular?
Graph the equation
• Y = -3x + 2
• Y = 1/3x -3
Graph the lines how do you know for
certain if the lines are perpendicular?
Graph the equation
• Y = 2x + 3
• Y = -1/2x + 2
Perpendicular lines
 Which of the following lines are perpendicular?
 3y = -9x -5
 6y – 2x = -5
 12x + 4y = 1
 Which of the following lines are perpendicular?
 3x + 2y =6
 3x -2y = 6
 6x + 4y = 6
Perpendicular lines
 What kind of slopes do parallel lines have?
 What kind of y-intercepts do parallel lines have?
 Why do parallel lines have the same slope?
 Why do parallel lines have different y-intercepts?
 What kind of slopes do perpendicular lines have?
 What kind of y-intercepts do perpendicular lines
have?
 What does opposite reciprocal mean?
Finding equations
 Find the Equation for the line described
 Passes through point (2, 4) parallel to
y = 2x – 5
 Passes through point (-3, 2) perpendicular to
y = -1/3x + 2
Finding equations
 Find the Equation for the line described
 Passes through point (-4, 5) parallel to
y = -3x + 2
 Passes through point (2, 4) perpendicular to
y = 2x + 2