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Learn how to graph quadratic functions by identifying the vertex, axis of symmetry, and y-intercept of a parabola. Practice graphing parabolas and solving related problems using a graphing calculator.
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4.1-4.2 Graphing Parabolas Objective: Students will graph using the vertex, axis of symmetry & y-intercept
The graph of a quadratic function, y = ax2+ bx + c, is a parabola. (U-shaped curve) Key parts x = -1 axis of symmetry: x=-1 Equation of a vertical line. vertex: (-1, -8) Ordered pair Minimum or Maximum (-2, -6) (0, -6) y-intercept: Ordered pair when x is 0. (-1, -8) Symmetry point: Reflect y-int. over axis.
Graphing Parabolas • The graph of a quadratic function, • y = ax2+ bx + c, is a parabola. (U-shaped curve) y = x2 + 4x - 7 Identify a, b, and c for these equations? y = 2x2 + 10x + 4 y = -3x2 + 5x + 9 • ifa is positive the graph opens up. • If a is negative the graph opens down.
Graphing Parabolas y = ax2 + bx + c Axis of symmetry: Vertex:
JUST WATCH a few--Graph the following parabola x = -2 y = x2 + 4x - 7 axis of symmetry: vertex: (0, -7) (-2, -11) y-intercept:
Graph the following parabola y = 2x2 + 10x + 4 (0, 4) axis of symmetry: vertex: (-5/2, -17/2) y-intercept:
Graph the following parabola Why did this parabola open downward instead of upward as did the previous two? y = -3x2 + 5x + 9 axis of symmetry: vertex: y-intercept:
hand-out Notes 4.1 • Complete notes together. • Classwork Worksheet 4.1B • Then, Show calculator steps..
Graphing Parabolas • With your graphing calculator, graph each of the following quadratic equations and identify the vertex (max or min) and axis of symmetry (vertical line). y = x2 + 4x - 7 y = x2 y = 2x2 + 10x + 4 y = -3x2 + 5x + 9
Classwork P. 244 #1-6 (Calculator practice) Homework p. 240 # 21-26, 44-46