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13.2 Solving Quadratic Equations by Graphing. CORD Math Mrs. Spitz Spring 2007. Objectives. Identify standard form coefficients in a standard formula Determine how a parabola opens Find the coordinates of the vertex Sketch a graph of a function. Assignment. 9.3 Worksheet A and B.
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13.2 Solving Quadratic Equations by Graphing CORD Math Mrs. Spitz Spring 2007
Objectives • Identify standard form coefficients in a standard formula • Determine how a parabola opens • Find the coordinates of the vertex • Sketch a graph of a function.
Assignment • 9.3 Worksheet A and B
Identify the values of a, b, and c in the functions. Standard form of a quadratic function: ax2 + bx + c a, b and c represent coeeficients in the function. a 0
Ex. 1: Identify the values of a, b, and c in the functions. y = -x2 + 4x – 8 a = -1 b = 4 c = -8
Tell whether the graph opens up or down. Write the equation of the axis of symmetry. If a is positive, the parabola opens up. If a is negative, the parabola opens down.
Ex. 2: Tell whether the graph opens up or down and state the equation of the axis of symmetry. The parabola opens up because a is positive 7.
Find the coordinates of the vertex. • In order to find the coordinates of the vertex, you must find the axis of symmetry, then plug in the value you find for x and determine the value for y.
Ex. 3 Find the coordinates of the vertex. Find the value for x using the formula for axis of symmetry.
Ex. 3 Find the coordinates of the vertex. Then substitute the value for x and solve for y. The vertex for this equation is at (1, 19).
Ex. 4: Find the coordinates of the vertex. Make a table of values using 2 x-values to the left and right of the vertex.
Ex. 4: Find the coordinates of the vertex. Make a table of values using 2 x-values to the left and right of the vertex.
Ex. 4: Find the coordinates of the vertex. Make a table of values using 2 x-values to the left and right of the vertex.
Ex. 4: Find the coordinates of the vertex. Make a table of values using 2 x-values to the left and right of the vertex.
Ex. 4: Find the coordinates of the vertex. Make a table of values using 2 x-values to the left and right of the vertex. Next step is to graph the points.