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Warm Up. Graphing Quadratic Functions. Graphing Quadratic Functions. Brainstorm everything you know about a quadratic function. THE GRAPH OF A QUADRATIC FUNCTION. The parabola opens up if a>0 and opens down if a<0. y = x 2.
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Graphing Quadratic Functions Brainstorm everything you know about a quadratic function.
THE GRAPH OF A QUADRATIC FUNCTION The parabola opens up if a>0 and opens down if a<0 y = x2 The parabola is wider than the graph of y = x2 if |a| < 1 and narrower than the graph of y = x2 if |a| > 1. vertex y = -x2 Axis of symmetry
STANDARD FORM Graph y = 2x2 -8x +6 Solution: The coefficients for this function Since a>0, the parabola opens up. The x-coordinate is: x = -b/2a The y-coordinate is: The vertex is a = 2, b = -8, c = 6. x = -(-8)/2(2) x = 2 y = 2(2)2-8(2)+6 y = -2 (2,-2).
GRAPH VERTEX: AXIS OF SYMMETRY: Y INTERCEPT:
VERTEX FORM OF QUADRATIC EQUATION y = a(x - h)2 + k • The vertex is (h,k). • The axis of symmetry is x = h.
GRAPHING A QUADRATIC FUNCTION IN VERTEX FORM Example y = -1/2(x + 3)2 + 4 VERTEX: AXIS OF SYMMETRY: Y INTERCEPT:
INTERCEPT FORM OF QUADRATIC EQUATION y = a(x - p)(x - q) • The x intercepts are p and q. • The axis of symmetry is halfway between (p,0) and (q,0).
GRAPHING A QUADRATIC FUNCTION IN INTERCEPT FORM Example y = -(x + 2)(x - 4). VERTEX: AXIS OF SYMMETRY: Y INTERCEPT: X INTERCEPT:
WRITING THE QUADRATIC EQUATION IN STANDARD FORM (1). y = -(x + 4)(x - 9) (2). y = 3(x -1)2 + 8 -x2 + 5x + 36 3x2 - 6x + 11