ACT SAT Prep Learn how to evaluate an expression for a given value

The video tutorial explains how to solve a given algebraic expression by first finding the value of X. The teacher guides through the process of isolating X in the equation 3X + 4 = -5, resulting in X = -3. The importance of using parentheses in calculations is emphasized to ensure correct order of operations. Finally, the expression X^2 - 4X is evaluated by substituting X = -3, leading to the final answer of 21.

Why is it important to use parentheses in mathematical expressions?

What is the final answer after evaluating the expression with the value of X?