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-1^2?! (binomial help!)

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    Was just doing some binomial expansion work expanding (2-x)^6

    6C0 * 2^6 * (-x)^0 = 64
    6C1 * 2^5 * (-x)^1 = -192x

    6C2 * 2^4 * (-x)^2 = 15*16*-1^2*x^2

    I typed the last line into my calculator, and I got -240x^2... But doesn't
    -1^2 = 1 ?!?!?

    so I typed that in, and -1^2 = -1. But if I type in -1*-1 = 1.

    What is going on? Have I made a rookie error somewhere? Why is my calculator telling me the answer is negative instead of positive? I was taught anything negative squared is positive!

    Is this a case of having to work out the negative power in my head, e.g odd power = negative and even power = positive?
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    Put in brackets...

    (-1)^2.
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    When doing on the calculator it does -(1)^2 i.e. it squares 1 first and the adds the minus sign. As mentioned above, put the entire -1 in brackets.
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    (Original post by lollage123)
    Was just doing some binomial expansion work expanding (2-x)^6

    6C0 * 2^6 * (-x)^0 = 64
    6C1 * 2^5 * (-x)^1 = -192x

    6C2 * 2^4 * (-x)^2 = 15*16*-1^2*x^2

    I typed the last line into my calculator, and I got -240x^2... But doesn't
    -1^2 = 1 ?!?!?

    so I typed that in, and -1^2 = -1. But if I type in -1*-1 = 1.

    What is going on? Have I made a rookie error somewhere? Why is my calculator telling me the answer is negative instead of positive? I was taught anything negative squared is positive!

    Is this a case of having to work out the negative power in my head, e.g odd power = negative and even power = positive?
    A negative squared is a positive but wehn you input -1^2, your calculator thinks you want to do -(1)^2, which would be -1.

    I do most of them in my head, or work them out individually to avoid mistakes such as that

    Hope I helped
  5. Offline

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    Casio calculators do this, others don't. It is the way the calculator carries out the order of operations.

    You can make it work by using brackets (-1)^2 or using the ANS button.

    Type -1 =

    ANS^2=

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