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anonymous

  • 5 years ago

I have to find the vertex of: y= -3x^2+12x-8 and I have to plot it on a graph, providing an ordered pair as the vertex. I'm not understanding this at all. How should I begin?

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  1. Owlfred
    • 5 years ago
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    Hoot! You just asked your first question! Hang tight while I find people to answer it for you. You can thank people who give you good answers by clicking the 'Good Answer' button on the right!

  2. anonymous
    • 5 years ago
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    complete the sqaure

  3. anonymous
    • 5 years ago
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    first factor out x^2 coeffiecnet

  4. anonymous
    • 5 years ago
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    y = -3 ( x^2 -4x ) -8

  5. anonymous
    • 5 years ago
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    note, we only factored out common factors on the x terms

  6. anonymous
    • 5 years ago
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    then complete the sqaure in side the brackets

  7. anonymous
    • 5 years ago
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    ok, it kinda makes sense so far..

  8. anonymous
    • 5 years ago
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    to complete the square on x^2 -4x , we need to half the -4 ( to get -2 ) , the square it , and add and subtract inside the brackets

  9. anonymous
    • 5 years ago
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    so y= -3 ( x^2 -4x + 4 - 4 ) - 8 // notice, its important you add and substract INSIDE THE BRACKET

  10. anonymous
    • 5 years ago
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    we need to maintain equality

  11. anonymous
    • 5 years ago
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    alright, with you on that

  12. anonymous
    • 5 years ago
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    now you group the perfect sqaure inside the bracket

  13. anonymous
    • 5 years ago
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    so y= -3 ( (x-2)^2 -4) -8

  14. anonymous
    • 5 years ago
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    now you expand the brackets , being careful with the signs

  15. anonymous
    • 5 years ago
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    so y= -3(x-2)^2 +12 -8

  16. anonymous
    • 5 years ago
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    So I'm seeing here the only way the vertex can be solved is by doing the equation, then plotting it on the graph- how would I plot this #1, and #2, how would I come up with a solution set??

  17. anonymous
    • 5 years ago
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    y= -3(x-2)^2 +4

  18. anonymous
    • 5 years ago
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    vertex = (2,4)

  19. anonymous
    • 5 years ago
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    you could do it other ways , you might the equation of axis of symmetry of a parabola is x=-b/2a

  20. anonymous
    • 5 years ago
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    And how to plot? I have to do it on an online graph. Totally confused with it

  21. anonymous
    • 5 years ago
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    and you know the vertex is on the axis of symmetry

  22. anonymous
    • 5 years ago
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    I dont know there, I know how to do a general plot but have idea how the computer with mark you

  23. anonymous
    • 5 years ago
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    "graph the equation by hand; find the vertex and round approximate coordinates to the second decimal place."

  24. anonymous
    • 5 years ago
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    "Use the graphing tool to graph the parabola"

  25. anonymous
    • 5 years ago
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    THIS is what is confusing me. Do I graph the solution set, I'm just not getting it. I understand for the most part the equation, but not plotting

  26. anonymous
    • 5 years ago
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    One more equation- (x+8)^2+8(x+7)=64. I can solve by the method of my choice

  27. anonymous
    • 5 years ago
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    Its not a negative sign in front of the x, I just need a solution set

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