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.

What is the first step in solving the equation 3X + 4 = -5?

• Multiply both sides by 3

• Subtract 4 from both sides

• Add 4 to both sides

• Divide both sides by 3

After isolating X, what is the value of X in the equation 3X = -9?

• 9

• -9

• 3

• -3

Why is it important to use parentheses when substituting the value of X into the expression X^2 - 4X?

• To simplify the expression

• To make the expression look neat

• To avoid division by zero

• To ensure the correct order of operations

What is the result of evaluating the expression (-3)^2 - 4(-3)?

• 0

• 21

• -21

• 9

What mistake did Michael make when evaluating the expression?

• He used the wrong value for X

• He forgot to use parentheses

• He multiplied instead of dividing

• He added instead of subtracting