_____ It is helpful if you use ordinary lower-case letters for variables (except in some formulas where upper-case letters are used). The symbol "×" is used to signify multiplication, so leads to confusion when you try to use it for a variable. In plain text, the exponentiation operator is a caret (^), so x^2 means "x squared", for example. If the exponent is supposed to include an arithmetic operation, then it needs to be enclosed in parentheses, x^(3y-4), for example.
