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Homework Help: Parenthesis conundrum

  1. Jun 30, 2016 #1

    tionis

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    Gold Member

    Hi guys. I'm asked to insert parentheses where needed so that the following expression evaluates to the given number negative 36:

    2 ⋅ 8 ÷ 4 - 20 = - 36

    My attempts:

    ( 2 ⋅ 8 ) ÷ ( 4 - 20 ) = 16 ÷ -16 = -1

    2 ⋅ ( 8 ÷ 4 ) - 20 = 2 ( 2 ) - 20 = -16

    ( 2 ⋅ 8 ÷ 4 ) - 20 = -16

    I just don't know what other combination I can try that will yield -36 as a solution. Please help me. Thanks.
     
  2. jcsd
  3. Jun 30, 2016 #2

    PeroK

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    Hint: 2 x -18 = -36

    If you'll forgive the lack of parenthesis!
     
  4. Jun 30, 2016 #3

    tionis

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    Gold Member

    I got it lol.

    2 ⋅ [ ( 8 ÷ 4 ) - 20 ] = 2 [ ( 2 ) - 20 ]
    = 2 [ -18] = -36

    Thank you so much, PeroK! You're AWESOME!






     
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