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anonymous

  • one year ago

The following table shows the length and width of two rectangles: Length Width Rectangle A x + 8 x − 1 Rectangle B 4x + 5 3x − 2 Which expression is the result of the perimeter of rectangle B minus the perimeter of rectangle A? 10x − 12 18x + 32 10x − 8 18x + 6

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  1. anonymous
    • one year ago
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    can someone help me on this?? i dont understand it

  2. jtvatsim
    • one year ago
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    Yikes! A little scary, huh? Not to worry though, it's actually pretty easy. Let's take it one step at a time.

  3. anonymous
    • one year ago
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    ok great

  4. jtvatsim
    • one year ago
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    The question sounds very confusing, "the perimeter of rectangle B minus the perimeter of rectangle A"... uh.. yeah. Let's just ignore that for now and think about the perimeters separately: Perimeter of rectangle A is (we will find out) and Perimeter of rectangle B is (again, we will find that out).

  5. anonymous
    • one year ago
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    okay

  6. jtvatsim
    • one year ago
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    So, what do we know about rectangle A? The table says that A's length is x + 8 (some number) and the width is x - 1 (some other number). Let's draw a picture so we can see what this even means.

  7. jtvatsim
    • one year ago
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    |dw:1436922996057:dw|

  8. jtvatsim
    • one year ago
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    Alright, does that picture make sense so far?

  9. anonymous
    • one year ago
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    yes, it does

  10. jtvatsim
    • one year ago
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    OK, perfect! We are almost done with the hardest part. Do you remember how to find the perimeter?

  11. anonymous
    • one year ago
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    you time it by each side ??

  12. anonymous
    • one year ago
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    times*

  13. jtvatsim
    • one year ago
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    Close, that's the area (they often get confused). :)

  14. jtvatsim
    • one year ago
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    It's actually easier... we just add all four sides together and measure the outside of the rectangle.

  15. anonymous
    • one year ago
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    ooh okay

  16. jtvatsim
    • one year ago
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    (x+8) + (x-1) + (x+8) + (x-1) = 4x + 16 - 2 = 4x + 14. There that's better.

  17. jtvatsim
    • one year ago
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    So that is the perimeter of A. Any questions on how we did that part?

  18. anonymous
    • one year ago
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    nope

  19. jtvatsim
    • one year ago
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    OK. Now, we just do exactly the same thing for rectangle B.

  20. jtvatsim
    • one year ago
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    We have different numbers: B width = 3x - 2 B length = 4x + 5

  21. jtvatsim
    • one year ago
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    |dw:1436923340928:dw|

  22. anonymous
    • one year ago
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    awesome

  23. jtvatsim
    • one year ago
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    And, then we just add all four sides... it's a little messy, but try it and see what you get. I'll check your answer. :)

  24. anonymous
    • one year ago
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    ok give me a second

  25. jtvatsim
    • one year ago
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    sure thing. take your time. :)

  26. anonymous
    • one year ago
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    4x+5+3x-2+4x+5+3x-2= 14x+6

  27. jtvatsim
    • one year ago
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    Excellent! Good job!

  28. jtvatsim
    • one year ago
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    Alright, so now we know that: Perimeter of A = 4x + 14 Perimeter of B = 14x + 6.

  29. anonymous
    • one year ago
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    so subtract 14x+6- 4x+14

  30. anonymous
    • one year ago
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    ?

  31. jtvatsim
    • one year ago
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    Good, but be careful with your parentheses. We want the whole perimeter of A to be subtracted so we need (14x + 6) - (4x + 14) in order to get the right answer.

  32. anonymous
    • one year ago
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    so its 10x-8 ??

  33. jtvatsim
    • one year ago
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    Exactly!

  34. anonymous
    • one year ago
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    YAYYY THANKYOU SO MUCH :))

  35. jtvatsim
    • one year ago
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    You're welcome! Good job!

  36. anonymous
    • one year ago
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    :)

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