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*_Artist_*

Simplify (-2 x - 9)(-4)can someone help me...No straight answers please...

  • 3 years ago
  • 3 years ago

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  1. polpak
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    You just have to distribute the multiplication to each term \[(a + b)(c) = ac + bc\]

    • 3 years ago
  2. *_Artist_*
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    Okay....

    • 3 years ago
  3. daria-m
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    why adding?

    • 3 years ago
  4. polpak
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    Why not?

    • 3 years ago
  5. daria-m
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    isnt it multiplying? (-2*-9)

    • 3 years ago
  6. polpak
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    So in your case you have (-2x -9)(-4) which is the same as (-2x + (-9))(-4)

    • 3 years ago
  7. polpak
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    Oh, is that x for multiplication? or is it an x.

    • 3 years ago
  8. daria-m
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    i think its multiplying... idk

    • 3 years ago
  9. *_Artist_*
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    i think it is just an x

    • 3 years ago
  10. daria-m
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    ohh ok

    • 3 years ago
  11. polpak
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    So did that make sense with what you need to do Artist, or do you need a bit more help?

    • 3 years ago
  12. *_Artist_*
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    I'm not sure....

    • 3 years ago
  13. polpak
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    Ok lets try this. When you multiply a sum (a + b + c+ ...) by a number k. You simply multiply each of the terms in the sum by that same number k.

    • 3 years ago
  14. polpak
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    So in your case, what is the sum you're multiplying ?

    • 3 years ago
  15. *_Artist_*
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    (-2 x - 9)(-4)

    • 3 years ago
  16. polpak
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    Not quite. (-2x - 9) is a sum.

    • 3 years ago
  17. polpak
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    Specifically it is the sum of -2x and -9

    • 3 years ago
  18. *_Artist_*
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    Okay

    • 3 years ago
  19. polpak
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    You know what a sum is right?

    • 3 years ago
  20. *_Artist_*
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    Yes...

    • 3 years ago
  21. polpak
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    Tell me =)

    • 3 years ago
  22. polpak
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    One of the most important things to learn in math is the vocabulary. Otherwise it is very difficult to understand what we are talking about if we aren't using the same words for things.

    • 3 years ago
  23. *_Artist_*
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    Okay.

    • 3 years ago
  24. polpak
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    What is a sum?

    • 3 years ago
  25. *_Artist_*
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    A sum is the answer of two numbers added together...

    • 3 years ago
  26. polpak
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    Close. Actually a sum is a sequence of terms added together. 2 is not a sum. 2 + 3 is a sum. 2*5 is not a sum. 2+3 + 2*5 is a sum.

    • 3 years ago
  27. *_Artist_*
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    Oh...Okay.

    • 3 years ago
  28. polpak
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    Now then. For each of the sums I listed above, count the number of terms in each sum.

    • 3 years ago
  29. *_Artist_*
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    2, then 4?

    • 3 years ago
  30. polpak
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    Close. But notice that the 2 is not being added to the 5, it's multiplied. The terms of a sum are _ONLY_ the things being added together.

    • 3 years ago
  31. polpak
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    So how many terms does that last sum have?

    • 3 years ago
  32. *_Artist_*
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    *Lightbulb*...Okay...

    • 3 years ago
  33. *_Artist_*
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    3?

    • 3 years ago
  34. polpak
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    I am glad I fanned you btw. You've been the best student I've seen here in a long time.

    • 3 years ago
  35. polpak
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    Yes, it has 3.

    • 3 years ago
  36. *_Artist_*
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    Really?

    • 3 years ago
  37. polpak
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    Yes.

    • 3 years ago
  38. *_Artist_*
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    I'm the best?

    • 3 years ago
  39. polpak
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    So far ;)

    • 3 years ago
  40. *_Artist_*
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    Cool...

    • 3 years ago
  41. polpak
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    Ok so now. Going back to what I was saying before.. If you have a number k multiplied by a sum. You simply distribute the multiplication of k to each term in the sum.

    • 3 years ago
  42. *_Artist_*
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    okay...

    • 3 years ago
  43. polpak
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    So lets look at your problem again.

    • 3 years ago
  44. polpak
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    (-2x - 9)(-4) What is the sum, and what is k?

    • 3 years ago
  45. *_Artist_*
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    the sum is (-2x-9)?

    • 3 years ago
  46. polpak
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    Yes!. But I get confused easily, so can you rewrite that as an equivalent sum (equals the same thing) so that it is explicitly two terms being _ADDED_ together?

    • 3 years ago
  47. polpak
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    Can you rewrite subtraction as adding a negative?

    • 3 years ago
  48. *_Artist_*
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    no...?

    • 3 years ago
  49. polpak
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    2-9 = 2+(-9) -7 = -7 Right?

    • 3 years ago
  50. *_Artist_*
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    Yes.

    • 3 years ago
  51. polpak
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    So do the same thing to the subtraction you have in your sum

    • 3 years ago
  52. polpak
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    I like my sums to only have addition.

    • 3 years ago
  53. polpak
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    feels neater ;p

    • 3 years ago
  54. *_Artist_*
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    Yeah...

    • 3 years ago
  55. *_Artist_*
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    so, -2x + (- 9,) ?

    • 3 years ago
  56. polpak
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    Yes.

    • 3 years ago
  57. polpak
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    So now you have this sum (-2x + -9) and you're multiplying it by (-4). So to do that you just multiply each term in the sum by the -4. (a + b)(c) = a*c + b*c

    • 3 years ago
  58. polpak
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    So what do you get?

    • 3 years ago
  59. *_Artist_*
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    -4*-2+ -4*-9?

    • 3 years ago
  60. polpak
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    Close. Don't forget your x.

    • 3 years ago
  61. *_Artist_*
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    8x + 36

    • 3 years ago
  62. *_Artist_*
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    like that?

    • 3 years ago
  63. polpak
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    Yes, exactly.

    • 3 years ago
  64. *_Artist_*
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    :)

    • 3 years ago
  65. polpak
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    Nice work!

    • 3 years ago
  66. *_Artist_*
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    Thank you!

    • 3 years ago
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