Lesson%203-2:%20Graphing

1
Lesson 3-2 Graphing

• Objective
• Students will graph order pairs in a relation
• Students will determine whether an ordered pair
  is a solution of an equation
• Students will graph equation by plotting several
  solutions

2

• Checking Solutions
• An ordered pair is a solution if it works in
  the relation.
• Is (1, 2) a solution to the relation y 2x?
• Substitute 1 for x and 2 for y
• 2 2(1) is true so yes.
• Is (4, 6) a solution?
• Substitute 4 for x and 6 for y
• 6 2(4) is false so no.
• Review the lesson at the following link
• What is a line?

3
Linear Equations y mx b (1st degree because
x x1)
Example 1 Slow method Put numbers in see what
comes out Graph the equation y 2x 1 x
y
-1
-3
-1
0
1
1
4
Faster Methodymxb

• mmove (slope) bbegin on y-axis
  (y-intercept)
• Example 2
• y 3x -1
• b -1 or (0,-1)
• m 3 or

(2,5)
(1,2)
(0,-1)
(-1,-4)
Can also drop 3 and go left 1 (2 negatives are
positive also!!)
5

• 2nd Degree Equations y x2
• Parabolas U shape graph
• Go to the following link.
• cool math link for parabolas
• Complete the intro and lesson 1 and answer the
  following
• 1.What is the Standard parabola guys job?
• 2.Draw the standard Parabola guy and label his
  points
• 3. Plotting points is for ______________________
• How does y x21 compare to the standard parabola
  guy?

6

• When there is a number hanging off of the
  standard parabola guy it is a ________shift.
• He moves _______if k is positive
• He moves _______if k is negative
• Extend
• 6. What would y -x2 look like? (multiplying
  the standard parabola guy by a negative 1) Graph
  and label it!

7
Domain Range Domain describes the x
values Range describes the y values Use
inequalities to tell what values x or y can be
Example 3 State the domain and range for the
following Use R for all real numbers a) y
-2x 3 b) y x2 - 5
Domain R Range R
Domain R Range y -5