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Why is the symbol “x” used in Mathematics to denote the unknown?

  1. Kevin Peter profile image71
    Kevin Peterposted 4 years ago

    Why is the symbol “x” used in Mathematics to denote the unknown?

    There are 25 other letters in the English alphabet. Then why was x particularly selected for this purpose?

  2. MickS profile image71
    MickSposted 4 years ago

    Because it is, that's way of the world, they same question could have been asked of any use of the other letters if they were used for the same purpose.

  3. fpherj48 profile image75
    fpherj48posted 4 years ago

    Kevin.....Probably because some genius mathematician,  Long ago....thought the X seemed more appropriate than the question mark..?????   Obviously, I am not related to that genius........LOL!

  4. connorj profile image76
    connorjposted 4 years ago


    I believe the answer is found in the ancient Greek/Roman culture primarily because of their number system; however, I have always loved this solution to this math problem.

    The question states: Find X
    Here is the equation: 10 = 3X - 2
    The answer is X=4; however, the answer I prefer is:
    The problem solver simply circles the letter X and declares "Here it is"

    1. MickS profile image71
      MickSposted 4 years agoin reply to this

      Yes, rather like 2+2.  The answer =4.  No it isn't, is, it =2+2, but has an element of fourness about it.

  5. portables profile image75
    portablesposted 4 years ago

    Is it because X marks the spot? so when you've found it then you know where the treasure is?

  6. profile image50
    luchorinposted 4 years ago

    well the premise of the question is false, the other letters are used as placeholders too. in number theory the convention is to use k, l, m, n, p, q for integers.  supposedly the tradition of using x started with rene descartes.  but algebra predates him, so obviously they were using other symbols before that.