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4.2 A : Graphing Quadratics in Vertex and Intercept Form. Graphing Quadratics in VERTEX FORM Y = a(x- h)² + k Vertex is ( h,k ) (↔ opposite, ↕) Axis of symmetry is x = h (x = x of vertex) a > 0 (positive) opens up a < 0 (negative) opens down IaI = stretch or shrink
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4.2 A : Graphing Quadratics in Vertex and Intercept Form • Graphing Quadratics in VERTEX FORM • Y = a(x- h)² + k • Vertex is (h,k) (↔ opposite, ↕) • Axis of symmetry is x = h (x = x of vertex) • a> 0 (positive) opens up • a < 0 (negative) opens down • IaI = stretch or shrink • Use TRANSFORMATIONS to graph!
Examples: Graph. Id vertex, axis of symmetry & max or min • 1. y = 2(x+1)² - 8 • 2. y = -(x-1)² + 5 • 3. y = ½ (x-3)² - 4
Graphing quadratics in Intercept (Factored) Form • INTERCEPT (factored) form • Y = a(x – p)(x – q) • X-intercepts= opposites of #’s in parenthesis • Vertex X value = • Vertex Y value = Put Vertex X value into original for all x’s & evaluate • Axis of symmetry: x= Vertex x value ()
Examples: graph. Id x-intercepts, vertex, axis of symmetry & max/min • 4. y = (x – 3) (x – 7 ) • 5. f(x) = 2(x – 4 ) (x + 1 ) • 6. y = - ( x + 1) (x – 5 )