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justinee Group Title

Can someone check this for me? (completing the square)

  • 11 months ago
  • 11 months ago

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  1. justinee Group Title
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    y = -2x^2 - 20x - 48

    • 11 months ago
  2. justinee Group Title
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    then i rewrote that into: y = -2(x^2 - 20x ____) -48 -20/2 = -10 then square it and I got 100 y = -2(x^2 - 20x +100) -48

    • 11 months ago
  3. justinee Group Title
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    then I added 100 to both sides and I got: y + 100= -2(x - 10)^2 -48 -100 -100 ------------------------ y = -2(x - 10)^2 - 148

    • 11 months ago
  4. halorazer Group Title
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    You subtracted 100 though ^

    • 11 months ago
  5. Decart Group Title
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    you add 48 to the other side and then also the 100 and the quadratic = 148

    • 11 months ago
  6. Decart Group Title
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    then you can factor the left side

    • 11 months ago
  7. justinee Group Title
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    can you show me that in steps? like from the beginning

    • 11 months ago
  8. Decart Group Title
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    you did it rite just set the equation = 0 then subtract 49 from both sides so 2x^2-20x=48

    • 11 months ago
  9. Decart Group Title
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    then complete the square and add the 100 to both sides

    • 11 months ago
  10. justinee Group Title
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    so it'd be 0 = -2(x^2 - 20x + 100) -48 ?

    • 11 months ago
  11. justinee Group Title
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    why do I need to factor that

    • 11 months ago
  12. justinee Group Title
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    Ok I got it thanks! and one more question

    • 11 months ago
  13. justinee Group Title
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    How would I solve: x^2 - 38x + c also by completing the square

    • 11 months ago
  14. Decart Group Title
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    c is a constant most likely just move it to the other side and complete the square

    • 11 months ago
  15. justinee Group Title
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    what is that going to give me?

    • 11 months ago
  16. Decart Group Title
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    x^2-38x=c

    • 11 months ago
  17. justinee Group Title
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    and what would be the next step

    • 11 months ago
  18. justinee Group Title
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    0 = (x2 - 38x ___) +c ?

    • 11 months ago
  19. Decart Group Title
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    square the -38 and do the same to both sides

    • 11 months ago
  20. Decart Group Title
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    (x^2-38x+__)=__-c

    • 11 months ago
  21. justinee Group Title
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    -38/2 = -19^2 = 361

    • 11 months ago
  22. Decart Group Title
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    yup

    • 11 months ago
  23. Decart Group Title
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    so that is on both sides

    • 11 months ago
  24. Decart Group Title
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    (x^2-38x+361)=361-c

    • 11 months ago
  25. justinee Group Title
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    okay so far i have: (x^2 - 38x + 361) = 361 -c

    • 11 months ago
  26. Decart Group Title
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    right now you should be able to factor the quadratic which is the point of completing the square

    • 11 months ago
  27. justinee Group Title
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    so like: ____ x___ = 361 ____+___= -38

    • 11 months ago
  28. Decart Group Title
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    right it will be the same number it is squared

    • 11 months ago
  29. justinee Group Title
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    -19

    • 11 months ago
  30. Decart Group Title
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    yup

    • 11 months ago
  31. justinee Group Title
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    (x-19)^2 = 361 - c?

    • 11 months ago
  32. Decart Group Title
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    and the first equation was x^2-10+25=49

    • 11 months ago
  33. Decart Group Title
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    right

    • 11 months ago
  34. justinee Group Title
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    what do I do now?

    • 11 months ago
  35. Decart Group Title
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    with the second you can't do anything it is most likely to show how you did the work

    • 11 months ago
  36. Decart Group Title
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    x-5=7

    • 11 months ago
  37. justinee Group Title
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    so just that ^

    • 11 months ago
  38. justinee Group Title
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    how would i write tht in intercept form

    • 11 months ago
  39. Decart Group Title
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    do you mean y=mx+b

    • 11 months ago
  40. justinee Group Title
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    no I also have to rewrite tht in intercept

    • 11 months ago
  41. Decart Group Title
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    the x intercept is +or-(7/5,0)

    • 11 months ago
  42. Decart Group Title
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    that is the y is 0

    • 11 months ago
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