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Letters in expressions and formulas

  1. Feb 5, 2014 #1
    Hello, first post for me so I am sorry if this is in the wrong topic.

    I'm am from the UK studying A-Level Physics.

    I understand some formulas but this is testing me. Before I message my tutor I thought I would try here. Looks like a very useful website.

    Letters in expressions and formulas.

    v2 = u2 + 2as

    I normally understand maths when I know the rules.

    2 × 5 is written as 2 × 5 or 10
    2 × a is written as 2a
    a × b is written as ab

    I don't seem to understand this and I can't seem to find helpful information and I will not skip the page.

    Sorry if this is in the wrong topic and thank you for your help.
  2. jcsd
  3. Feb 5, 2014 #2


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    Staff: Mentor

    Do you mean ##u^2## and ##v^2##, with the 2 small and high? In that case, it is called an exponent and, in the present case, means "squared":
    u^2 = u \times u
    v^5 = v \times v \times v \times v \times v
    You can have a look at Wikipedia for what it means when the exponent is not a positive integer.
  4. Feb 5, 2014 #3


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    Multiplication is used so much in maths that it's simply much easier to get rid of the [itex]\times[/itex] symbol. This also meant that the letter [itex]x[/itex] could be used as a variable (and it's used a lot) without running into problems of ambiguity between it being a variable or a multiplication symbol.

    Whenever you have a situation like [itex]2\times 5[/itex] then you're expected to evaluate that to 10, while [itex]2\times a=2a[/itex] cannot be simplified further so it's ok to leave as it is.

    Other than that, I don't see what's so confusing about the notation.
  5. Feb 5, 2014 #4
    Yes, small 2 above the u.

    Thank you for your help. I'll see how I get on.
  6. Feb 5, 2014 #5


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    You must have missed a couple of days in algebra class.
  7. Feb 5, 2014 #6


    Staff: Mentor

    Grog85, if you're going to be studying physics, you'll need to get the algebra difficulties squared away first.
  8. Feb 5, 2014 #7


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