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  • View Poll Results: Is -2^2 equal to 4 or -4?
    4
    53.85%
    -4
    46.15%

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    There was a thread on this a few days ago and a big discussion but I didn't understand what the actual answer was. Is -2^2 equal to 4 or -4? I've made a poll for you people to vote.

    Personally I think it's 4 since a square is always positive but there were some crazy people who said it was -4. What do others think?

    Also my friend told me that 0.999...=1. I'm not sure if he was joking since there's always a really really small difference between the approximations and 1. I'm pretty sure it's not true but can anyone confirm it?
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    because you haven't put any brackets in there it is -4!
    (-2)^2 = 4


    edit: the 0.9 recurring could be considered to be 1 for ease but it is technically not!
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    0.9* (the star equals recurring) does equal 1 in theory.

    It depends on the context.

    (-2)^2 = 4
    -(2^2)=4
    -2^2 can be either.
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    It's -4 if you read it as -(2^2), or 4 if you read it as (-2)^2. If you were to read it following the rules of which sign you read first,* it would be -4 as you always perform index operations (like squaring or cubing) before anything else (unless it's in a bracket).

    Edit: *Ah, BODMAS. I remember... I never forgot... I'm sleep deprived ok!? :p:
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    Oh my god.

    -2^2 is -4. BODMAS will tell you this, because -2^2 means "square the 2, then put a - in front of it". (-2)^2 is +4, because two minuses will cancel. It's notation. It's not open to debate - unless you put those brackets in, writing "-2^2" means "-(2^2)" by default.

    And yes, 0.999... = 1. The typical argument against this goes something like "yeah, but, there's a difference of 0.000...(infinitely many)...001 between them", but there's no such thing as infinitely many zeroes and then a 1 at the end.

    Can we please leave this?
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    (Original post by studentbug)
    There was a thread on this a few days ago and a big discussion but I didn't understand what the actual answer was. Is -2^2 equal to 4 or -4? I've made a poll for you people to vote.

    Personally I think it's 4 since a square is always positive but there were some crazy people who said it was -4. What do others think?

    Also my friend told me that 0.999...=1. I'm not sure if he was joking since there's always a really really small difference between the approximations and 1. I'm pretty sure it's not true but can anyone confirm it?
    1=\frac{9}{9}=9\times\frac{1}{9}  =9\times0.111...=0.999\ldots. It's true
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    With Brackets = 4
    Without = -4
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    -2 \times -2 = 4 aka [/latex] (-2)^2 = 4[/latex], because the two minuses cancel each other out.

    Verbally, it depends on how you say it. If you pause after minus 2 (minus two, squared) then that implies that you square the -2, but if you say it all together (minustwosquared) or pause after the minus (minus *pause* two squared), then you square the two and make the resultant answer negative.
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    (Original post by generalebriety)
    Oh my god.

    -2^2 is -4. BODMAS will tell you this, because -2^2 means "square the 2, then put a - in front of it". (-2)^2 is +4, because two minuses will cancel. It's notation. It's not open to debate - unless you put those brackets in, writing "-2^2" means "-(2^2)" by default.

    And yes, 0.999... = 1. The typical argument against this goes something like "yeah, but, there's a difference of 0.000...(infinitely many)...001 between them", but there's no such thing as infinitely many zeroes and then a 1 at the end.

    Can we please leave this?
    yes i agree we leave this. it is a dumb question a 12 year old should be able to answer!
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    (Original post by chr15chr15)
    edit: the 0.9 recurring could be considered to be 1 for ease but it is technically not!
    Yes it is.
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    Thanks for your opinions - hope I'm not causing any offence!

    Surely -2^2 is given by substituting -2 into the graph of x^2? That would say it's 4 I thought. Maybe it's ambiguous?

    Why can't you have infinitely many zeros and then a 1? We have imaginary numbers after all.
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    (Original post by RightSaidJames)
    [latex[-2 x -2 aka -2^2 = 4[/latex], because the two minuses cancel each other out.
    I'm going to start neg repping people if they will continue to spread such utter ********. I've never seen such a bunch of misinformed people in my life. Can one of you just use your brain and a bit of primary school BODMAS-style thinking to get the correct answer of -4 and then accept it, please?
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    (Original post by boy)
    1=\frac{9}{9}=9\times\frac{1}{9}  =9\times0.111...=0.999\ldots. It's true
    but 1/9 does not equal 0.111...
    i know your gonna come up with some stuff that its infinitely close so we can say it is, but its a fact it isn't!
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    (Original post by studentbug)
    Thanks for your opinions - hope I'm not causing any offence!

    Surely -2^2 is given by substituting -2 into the graph of x^2? That would say it's 4 I thought. Maybe it's ambiguous?
    You're talking about (-2)^2, which is definitely 4. I'm talking about -(2^2), which is definitely -4. I hope we agree this far. The notation -2^2 is not ambiguous - it is universally accepted to mean the latter.

    (Original post by studentbug)
    Why can't you have infinitely many zeros and then a 1? We have imaginary numbers after all.
    Because it doesn't make sense. Imaginary numbers do - you might not be able to hand me -3i apples, but it's mathematically sensible and consistent.
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    (Original post by chr15chr15)
    but 1/9 does not equal 0.111...
    i know your gonna come up with some stuff that its infinitely close so we can say it is, but its a fact it isn't!
    OK (not that the point raised is correct), consider the following series:

     0.9 + 0.09 + 0.009 + ... .

    This is equal to the recurring decimal in question.

    Now sum the series to infinity:

     \frac{0.9}{1 - 0.1} = 1 .
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    ^^^1/9 is 0.111. Check with your calculator
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    (Original post by chr15chr15)
    but 1/9 does not equal 0.111...
    i know your gonna come up with some stuff that its infinitely close so we can say it is, but its a fact it isn't!
    There's no such thing as "infinitely close". 1 and 0.999... are exactly the same thing.
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    Guys, we had a thread like this the other day, please stop creating them. Generalebriety has explained it well, so I'm closing this before it becomes another 8 page spam-fest.
 
 
 
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