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Example 4 Graph f(x) = x^2 -2x - 8

Steps to Graph ax^2 + bx + c

  • Find the vertex and the axis of symmetry. Sketch these in.
  • Find the x-intercept by plugging in 0 for y.
  • Find the y-intercept by plugging in 0 for x.
  • Reflect your points across the axis of symmetry and connect your dots with a smooth U-shaped (not V-shaped) curve.

Graph f(x) = x^2 -2x - 8 

  1. the axis of symmetry is -9

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for now I'm just gonna type my work and figure out what to do next

  1. fubd the line of symetrym -(b/2a)=x
  2. a = 1, b = -2, c = -8
  3. use this to find vertex
  4. 1^2 + -2 * 1 - 8= 1- 2 - 8 = -9 = y
  5. the vertex is x, -9
  6. find the axis of symetry
  7. the axis of symmetry is -9
  8. so so