Question 352 of 480
Which of the following expressions is equivalent to \( (2^3 \times 2^{-1})^2 \) in standard form?
- \( 2^4 \)
- \( 2^6 \)
- \( 2^{10} \)
- \( 2^2 \)
Correct Answer:
B
Explanation
To solve the expression \( (2^3 \times 2^{-1})^2 \) and find its equivalent in standard form, let's break it down step-by-step.
### Step 1: Simplify the expression inside the parentheses
The expression inside the parentheses is \( 2^3 \times 2^{-1} \). When multiplying powers with the same base, we add the exponents. This is based on the exponent rule:
\[
a^m \times a^n = a^{m+n}
\]
Applying this rule here:
\[
2^3 \times 2^{-1} = 2^{3 + (-1)} = 2^{3 - 1} = 2^2
\]
### Step 2: Raise the result to the power of 2
Now we take the result from Step 1, which is \( 2^2 \), and raise it to the power of 2:
\[
(2^2)^2
\]
When raising a power to another power, we multiply the exponents. This is another exponent rule:
\[
(a^m)^n = a^{m \times n}
\]
Applying this rule:
\[
(2^2)^2 = 2^{2 \times 2} = 2^4
\]
### Final Answer
Thus, the expression \( (2^3 \times 2^{-1})^2 \) simplifies to \( 2^4 \).
### Correct Option
The correct option is **A. \( 2^4 \)**.
### Explanation of Other Options
- **B. \( 2^6 \)**: This option is incorrect because it suggests that the exponent should be 6. However, we calculated the exponent to be 4, not 6.
- **C. \( 2^{10} \)**: This option is also incorrect. It implies a much larger exponent than what we derived. The calculations show that the exponent is 4, not 10.
- **D. \( 2^2 \)**: This option is incorrect as well. While \( 2^2 \) was an intermediate result, it was not the final answer after raising it to the power of 2.
### Common Pitfalls
1. **Forgetting to add exponents**: When multiplying powers, always remember to add the exponents.
2. **Misapplying exponent rules**: Ensure you apply the correct rules for multiplying and raising powers.
3. **Not simplifying step-by-step**: Itβs important to simplify expressions step-by-step to avoid confusion.
### Revision Summary
- When multiplying powers with the same base, add the exponents: \( a^m \times a^n = a^{m+n} \).
- When raising a power to another power, multiply the exponents: \( (a^m)^n = a^{m \times n} \).
- The expression \( (2^3 \times 2^{-1})^2 \) simplifies to \( 2^4 \).
- The correct answer is **A. \( 2^4 \)**.