Section 8.6 Quadratic Functions & Graphs Graphing Parabolas f(x)=ax 2 f(x)=ax 2 +k f(x)=a(x–h) 2 f(x)=a(x–h) 2 +k Finding the Vertex and Axis of Symmetry Finding Maximums or Minimums 8.61
Definition Let’s make a table of values for f(x) = x 2 Then sketch the basic parabola shape … 8.62
Make a table of values for f(x) = x 2 Then graph it 8.63
Similar Curves Changing the coefficient of x 2 : Smaller is wider Larger is narrower The vertex remains the same 8.64
Make a table of values for f(x) = -½x 2 Then graph it 8.65
Reflections The graph of y= -ƒ(x) is the graph of y = ƒ(x) reflected about the x-axis. 8.66
Vertical Translations If ƒ is a function and k is a positive number, then The graph of y = ƒ(x) + k is identical to the graph of y =ƒ(x) except that it is translated k units upward. The graph of y = ƒ(x) - k is identical to the graph of y = ƒ(x) except that it is translated k units downward. Sketch f(x) = x on the board 8.67
Horizontal Translations If ƒ is a function and h is a positive number, Then the graph of y = ƒ(x - h) is identical to the graph of y = ƒ(x) except that it is translated h units to the right. The graph of y = ƒ(x + h) is identical to the graph of y = ƒ(x) except that it is translated h units to the left. 8.68
Graph f(x) = (x – 3)
Graph g(x) = -2(x +4)
8.611
Graph g(x) = (x – 3) 2 –
Finding the Vertex and Axis of Symmetry Answer the following questions about the given equation: a. Does the graph open upward or downward? b. What are the coordinates of the vertex? c. What is the axis of symmetry? d. Is it narrow or wide? Up (5,1) x=5 narrow 8.613
Finding the Vertex and Axis of Symmetry Answer the following questions about the given equation: a. Does the graph open upward or downward? b. What are the coordinates of the vertex? c. What is the axis of symmetry? d. Is it narrow or wide? Down (-4,-3) x=-4 wide 8.614
Maximums & Minimums 8.615
Maximum or Minimum? Vertex and Axis of Symmetry? 8.616
But what if the function is not in the form of f(x) = a(x – h) 2 + k ? 8.617
What Next? Section 9.1 Section 9.1 Composite Functions Sections may not be covered