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Inopeki

FOILing, do i multiply or add? Like (2x+4)+(2x+4) i add there, right? And (2x+4)*(2x+4) I multiply there, right?

  • 2 years ago
  • 2 years ago

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  1. satellite73
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    yes

    • 2 years ago
  2. Inopeki
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    I did that in class todya but i didnt get the right answer..

    • 2 years ago
  3. satellite73
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    what did you get for the first one?

    • 2 years ago
  4. Inopeki
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    (2x+4)+(2x+4) 4x+2x+4+4+2x+4+4 8x+16

    • 2 years ago
  5. satellite73
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    hmm

    • 2 years ago
  6. satellite73
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    it looks like you are multiplying and adding instead of adding. the parentheses here are unnecessary

    • 2 years ago
  7. amistre64
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    when it says to add, I would add. and when it says to multiply, id multiply. but thats just me set in my ways :)

    • 2 years ago
  8. satellite73
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    \[(2x+4)+(2x+4)=2x+4+2x+4=2x+2x+4+4\]

    • 2 years ago
  9. satellite73
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    let's imagine for a moment that x was ten (x is a variable, but it could be ten) then \[2x+4=2\times 10+4=24\] and \[24+24=48\]

    • 2 years ago
  10. Inopeki
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    I thought it was like this |dw:1327066387934:dw|

    • 2 years ago
  11. satellite73
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    multiplication distributes over addition. so if you had \[(2x+4)(2x+4)\] you would use the distributive law, just like if you had \[24\times 24\]

    • 2 years ago
  12. Inopeki
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    But wheres the x?

    • 2 years ago
  13. Tomas.A
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    addition is commutative you can remove brackets when you have ONLY addition

    • 2 years ago
  14. satellite73
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    but addition is the same as "combine like terms" just as you would with arithmetic 24 + 24 ______ 48 2x + 4 + 2x + 4 __________ 4x + 8

    • 2 years ago
  15. amistre64
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    2x+4 (+) 2x+4 -------- 4x+ 8 2x+4 (x) 2x+4 --------- 8x+16 4xx+8x ----------------- 4x^2+16x+16

    • 2 years ago
  16. Inopeki
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    Why would it be 4x^2+16x+16?

    • 2 years ago
  17. satellite73
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    @inopeki i was making an analogy. the work you do with variables is a generalization of the work you do in arithmetic, and if it doesn't work with arithmetic it certainly doesn't work with variables, because the variable could be a number, that is you could replace the variable by a number

    • 2 years ago
  18. amistre64
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    becasue thats what happens when you multiply stuff

    • 2 years ago
  19. Inopeki
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    Oh ok

    • 2 years ago
  20. Inopeki
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    so basically just add them up?

    • 2 years ago
  21. Inopeki
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    2x+4 (+) 2x+4 -------- 4x+ 8

    • 2 years ago
  22. satellite73
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    imagine your job was to add \[24+24\]\ what would you do? line them up and add

    • 2 years ago
  23. amistre64
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    5+3 = 8 (x) 2+4 = 6 ------------ 20+12 10+6 -------------- 10+26+12 = 48

    • 2 years ago
  24. Inopeki
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    24 +24 ---- 48

    • 2 years ago
  25. satellite73
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    and similarly 2x + 4 + 2x + 4 __________ 4x + 8

    • 2 years ago
  26. Inopeki
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    Oh! Give me another example?

    • 2 years ago
  27. satellite73
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    \[(3x+5)+(4x+1)\]

    • 2 years ago
  28. Inopeki
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    (3x+5) +(4x+1) -------- 7x+6

    • 2 years ago
  29. satellite73
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    that's it!

    • 2 years ago
  30. Inopeki
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    Yes! :D Thanks

    • 2 years ago
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