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monkey*

  • one year ago

Given f(x)=-x^2+2x, find f(-3).

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  1. monkey*
    • one year ago
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    Help?

  2. Nnesha
    • one year ago
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    f(-3) means x=-3 so substitute all x's for -3

  3. monkey*
    • one year ago
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    So, f(-3)=-3^2+2(-4) ?

  4. monkey*
    • one year ago
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    (-3)**

  5. Nnesha
    • one year ago
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    yes right remember coefficient is also negative so \[\huge\rm -(-3)^2+2(-3)\] now solve

  6. monkey*
    • one year ago
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    3?

  7. Nnesha
    • one year ago
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    hmm no (-3)^2 =?

  8. monkey*
    • one year ago
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    -6?

  9. Nnesha
    • one year ago
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    (-3)^2 is same as -3 times -3

  10. monkey*
    • one year ago
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    9.

  11. Nnesha
    • one year ago
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    yes right so-(9)+2(-3) = ?

  12. monkey*
    • one year ago
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    I got -15.

  13. Nnesha
    • one year ago
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    right

  14. monkey*
    • one year ago
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    Would that be my final answer?

  15. Nnesha
    • one year ago
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    yes

  16. monkey*
    • one year ago
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    Okay, would you mind helping me with just one more?

  17. Nnesha
    • one year ago
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    i'll try

  18. monkey*
    • one year ago
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    If f(x)=x-3 and g(x)=2x-4, find (f+g)(x).

  19. monkey*
    • one year ago
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    I tried working this one out and got 3x-7. Which I don't think is right.

  20. Nnesha
    • one year ago
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    just one question how did you get 3x :=)

  21. monkey*
    • one year ago
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    I have no idea honestly. Haha

  22. Nnesha
    • one year ago
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    so how did you get 3x-7 ?

  23. monkey*
    • one year ago
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    At the end how it has f+g and then x. I think that's how I got the x. Can you help?

  24. Nnesha
    • one year ago
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    (f+g)(x) means add both function f(x) and g(x) so f(x) + g(x)

  25. Nnesha
    • one year ago
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    so replace f(X) with x-3 and f(x) with 2x-4 and then combine like terms (x-3)+(2x-4)

  26. monkey*
    • one year ago
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    Wouldn't you add the x to 2x and it becomes 3x?

  27. Nnesha
    • one year ago
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    yes right that's what i was asking

  28. Nnesha
    • one year ago
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    good job!

  29. monkey*
    • one year ago
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    Thank you, so now the -3 and -4¿

  30. monkey*
    • one year ago
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    ?

  31. Nnesha
    • one year ago
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    yes right -3-4 are like terms

  32. monkey*
    • one year ago
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    Would it be -7?

  33. monkey*
    • one year ago
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    Ohh, would my answer actually be 3x-7?

  34. Nnesha
    • one year ago
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    yes right

  35. monkey*
    • one year ago
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    Thank you so much for the help!

  36. Nnesha
    • one year ago
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    yw :=)

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