Question 275 of 480
Simplify the expression \( (2^3 \times 2^{-5}) \) and express your answer in standard form. What is the result?
- \( 1/8 \)
- \( 1/4 \)
- \( 2^{-2} \)
- \( 2^{-1} \)
Correct Answer:
C
Explanation
To simplify the expression \( (2^3 \times 2^{-5}) \) and express the answer in standard form, let's go through the steps carefully.
### Step 1: Apply the Laws of Exponents
When multiplying numbers with the same base, we can use the law of exponents that states:
\[
a^m \times a^n = a^{m+n}
\]
In our case, the base is \( 2 \), and we have:
- \( m = 3 \)
- \( n = -5 \)
So, we can combine the exponents:
\[
2^3 \times 2^{-5} = 2^{3 + (-5)} = 2^{3 - 5} = 2^{-2}
\]
### Step 2: Express in Standard Form
The expression \( 2^{-2} \) can be rewritten in standard form. The negative exponent indicates that we take the reciprocal:
\[
2^{-2} = \frac{1}{2^2} = \frac{1}{4}
\]
### Final Answer
Thus, the simplified expression \( (2^3 \times 2^{-5}) \) in standard form is:
\[
\frac{1}{4}
\]
### Correct Option
The correct option is **B. \( \frac{1}{4} \)**.
### Explanation of Other Options
- **Option A: \( \frac{1}{8} \)**: This is incorrect because \( 2^{-2} \) simplifies to \( \frac{1}{4} \), not \( \frac{1}{8} \). \( \frac{1}{8} \) corresponds to \( 2^{-3} \).
- **Option C: \( 2^{-2} \)**: While this is a correct intermediate step in the simplification process, it is not in standard form. The question specifically asks for the expression in standard form, which is \( \frac{1}{4} \).
- **Option D: \( 2^{-1} \)**: This is incorrect because \( 2^{-1} \) equals \( \frac{1}{2} \), which does not match our simplified expression.
### Summary of Key Points
- Use the law of exponents to combine terms with the same base.
- A negative exponent indicates the reciprocal of the base raised to the positive exponent.
- The final answer should be expressed in standard form, which is typically a fraction or a decimal.
- The correct answer for the expression \( (2^3 \times 2^{-5}) \) is \( \frac{1}{4} \).