Recent content by SergeantAngle

  1. S

    High School What does \sum\limits_{i\neq j}^N a_i a_j mean in summation notation?

    Okay, thanks.
  2. S

    High School What does \sum\limits_{i\neq j}^N a_i a_j mean in summation notation?

    Hi I have a textbook which uses the notation: \sum\limits_{i\neq j}^N a_i a_j I can't find anywhere what this actually means. Is it equivalent to: \sum\limits_{i}^N \sum\limits_{j}^N a_i a_j where j can't equal i? Thanks.