1. The problem asks to represent the phrase "7 is subtracted from the square of a number" as an algebraic expression. 2. Let the number be represented by the variable $x$. 3. The square of the number is written as $x^2$. 4. "7 is subtracted from the square of a number" means we take the square of the number and then subtract 7 from it. 5. Therefore, the algebraic expression is $$x^2 - 7$$. 6. No simplification is needed as per the problem instructions.