Question 266 of 480
What is the result of simplifying the expression \( (2^3 \times 2^4) \div 2^5 \) using the laws of indices?
- \( 2^2 \)
- \( 2^0 \)
- \( 2^1 \)
- \( 2^5 \)
Correct Answer:
A
Explanation
To simplify the expression \( (2^3 \times 2^4) \div 2^5 \) using the laws of indices, let's break it down step by step.
### Step 1: Apply the Law of Indices for Multiplication
The first part of the expression is \( 2^3 \times 2^4 \). According to the laws of indices, when you multiply two powers with the same base, you add the exponents. This can be expressed as:
\[
a^m \times a^n = a^{m+n}
\]
In our case:
\[
2^3 \times 2^4 = 2^{3+4} = 2^7
\]
### Step 2: Rewrite the Expression
Now, we can rewrite the original expression using the result from Step 1:
\[
(2^3 \times 2^4) \div 2^5 = 2^7 \div 2^5
\]
### Step 3: Apply the Law of Indices for Division
Next, we need to simplify \( 2^7 \div 2^5 \). According to the laws of indices, when you divide two powers with the same base, you subtract the exponents. This can be expressed as:
\[
\frac{a^m}{a^n} = a^{m-n}
\]
Applying this to our expression:
\[
2^7 \div 2^5 = 2^{7-5} = 2^2
\]
### Final Result
Thus, the simplified result of the expression \( (2^3 \times 2^4) \div 2^5 \) is:
\[
2^2
\]
### Conclusion
The correct option is **A. \( 2^2 \)**.
### Explanation of Other Options
- **B. \( 2^0 \)**: This option is incorrect because \( 2^0 = 1 \), which does not match our result of \( 2^2 \).
- **C. \( 2^1 \)**: This option is also incorrect. \( 2^1 = 2 \), which is not the result we obtained.
- **D. \( 2^5 \)**: This option is incorrect as well. \( 2^5 = 32 \), which is not related to our simplified expression.
### Common Pitfalls
- **Forgetting to add or subtract exponents**: It's crucial to remember the correct operations (addition for multiplication and subtraction for division).
- **Misapplying the laws of indices**: Ensure that the base remains the same when applying these laws.
### Revision Summary
- Use \( a^m \times a^n = a^{m+n} \) for multiplication of powers.
- Use \( \frac{a^m}{a^n} = a^{m-n} \) for division of powers.
- Always check that the base is the same when applying these laws.
- The final answer for \( (2^3 \times 2^4) \div 2^5 \) is \( 2^2 \).