• rasensprenger@feddit.de
    link
    fedilink
    English
    arrow-up
    3
    ·
    edit-2
    10 months ago

    The square root of x is usually defined as the positive real number that squares to x, so x^2 = 4 => x = ±2 but sqrt(4) = 2, not ±2

    The complex sqrt function is multivalued, but that opens a whole other can of worms

    • digdug@kbin.social
      link
      fedilink
      arrow-up
      6
      ·
      10 months ago

      And even if you allowed sqrt(4) = ±2, it would still be invalid to evaluate it to -2 on one side of the equation, but then use +2 on the other side.