Graphing Parabolas              

                     Lesson 1

          Parabolas are of quadratic form y= ax² + bx +c

          If a is positive, then the parabola will open upward and has minimum point.

          If a is negative, the parabola will open downward and has maximum point.

Problem:    Will the graph of parabola y = 3x² + 2x - 8 open upward or downward?

Solution      The parabola has equation in the quadratic form y= ax² + bx +c

Step 1:

Solution     Comparing y = 3x² + 2x − 8 with the equation y= ax² + bx +c,

                                                            Step 2:         A = 3, b = 2 and c = −8                                                             

Solution     If a is Positive, the parabola will open upward  and has minimum  point.

Step 3:  

                                                            Solution    Answer: Upward

Step 4:

Complete

                                                            Try two practice problems:

A.	Will the graph of parabola y = −5x² − 2x + 3 open downward or upward?
B.	for the graph y= 3x² − 5x − 4 What is the equation of the axis of symmetry?

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