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that1chick

how do you write y = 2x2 + 6x + 4 in general form?

  • one year ago
  • one year ago

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  1. iheartfood
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    do u know the general form?

    • one year ago
  2. that1chick
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    yes, y=a(x-h)^2+k

    • one year ago
  3. iheartfood
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    did u need it in linear form?

    • one year ago
  4. iheartfood
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    like the general form of a linear equation?

    • one year ago
  5. that1chick
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    just the general form of a quadratic equation

    • one year ago
  6. iheartfood
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    okay, so u need to know the quadratic formula i believe..do u know it?

    • one year ago
  7. that1chick
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    general form> y=a(x-h)^2+k

    • one year ago
  8. that1chick
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    oh, yeah!

    • one year ago
  9. that1chick
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    quadratic formula> -b+-sqrt(b-4(a)(c))/2(a)

    • one year ago
  10. that1chick
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    but how does that help convert it to general form?

    • one year ago
  11. that1chick
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    I thought it just helped find the x-intercepts..

    • one year ago
  12. iheartfood
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    if i can remember this correctly, i believe u need to first solve to get the values of a,b,c and then you just plug it into the general form... I'm not 100% sure tho... @abb0t, am i remembering this correctly? ;/

    • one year ago
  13. that1chick
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    I know how to convert it... the problem is the 2 in 2x^2

    • one year ago
  14. abb0t
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    General form of what?

    • one year ago
  15. that1chick
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    quadratic equations

    • one year ago
  16. that1chick
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    2 in 2x^2 is the problem.... you isolate the x variables getting: y-4=2x^2+6x then complete the square and balance the equation: 6/2=3 3^2=9, y-4+9=2x^2+6x+9, y+5=2x^2+6x+9 then convert the trinomial into a binomial... thus lies my dilemma

    • one year ago
  17. iheartfood
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    sorry, i'm not very sure, cuz i don't think i remember this correctly ahha and i don't wanna help u wrongly haha @Mertsj probs knows :) good luck!!! :D

    • one year ago
  18. that1chick
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    thanks (:

    • one year ago
  19. Mertsj
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    \[y=2x^2+6x+4\] \[y=2(x^2+3x+______ )+4\]

    • one year ago
  20. Mertsj
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    Now complete the square by adding (3/2)^2 inside the parentheses: \[y=2(x^2+3x+(\frac{3}{2})^2)+4-\frac{9}{2}\]

    • one year ago
  21. Mertsj
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    Now factor: \[y=2(x+\frac{3}{2})^2-\frac{1}{2}\]

    • one year ago
  22. that1chick
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    why 3/2?

    • one year ago
  23. Mertsj
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    I want to show you something: \[x^2+6x+9=(x+3)^2\]

    • one year ago
  24. Mertsj
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    \[x^2+8x+16=(x+4)^2\]

    • one year ago
  25. that1chick
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    I don't get what you did with: (3/2^2)+4−92

    • one year ago
  26. Mertsj
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    Notice the relationship between the coefficient of x and the constant term in a trinomial square.

    • one year ago
  27. Mertsj
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    If you take 1/2 the coefficient and square it, you get the constant term.

    • one year ago
  28. Mertsj
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    So I took 1/2 of 3 and got 3/2. Then I squared it and added it to the x^2 + 3x to get a trinomial square.

    • one year ago
  29. Mertsj
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    Now the (3/2)^2 was inside a parenthesis which has a 2 in front of it so I was really adding 2 times (3/2)^2 which is 2 times 9/4 which is 9/2. So since I could not change the equation, I then had to subtract 9/2.

    • one year ago
  30. Mertsj
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    Follow me?

    • one year ago
  31. that1chick
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    I think so

    • one year ago
  32. that1chick
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    Okay, yes! I get what you did (: thank you! what were you trying to show me with those other two equations?

    • one year ago
  33. Mertsj
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    The relationship between the coefficient of x and the constant term.

    • one year ago
  34. that1chick
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    oh, that half of the coefficient of x to the second power = the constant. okay, cool

    • one year ago
  35. that1chick
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    Thank you for helping me (:

    • one year ago
  36. Mertsj
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    yw

    • one year ago
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