Expansion - Explanation with Area of Square (Question 1)


  1. Sandy,

    If we look at the expression within the bracket, it's (x-9), which can be interpreted that we have a length that is "x"; then subtract by 9.

    So, the entire length of the square would be "x".
    When subtract by 9, it means now the length is made up by 2 parts: one part "x", the other part would be the remaining part "x-9".

    Hope the above helps you to get a clearer idea. Please re-draw to see if you could figure what it means.

    Next, the working in the 2nd photo is not clear. Is that something you get out from the FOIL method? Hm... then need to use arrows to show the working.
    Please re-post.

  2. Thanks. I really don't know how to represent it in a rectangle. I will re-post.