Question 264 of 480
What is the result of simplifying the expression \( (3 \times 10^4) \times (2 \times 10^3) \) and writing it in standard form?
- \( 6 \times 10^7 \)
- \( 6 \times 10^6 \)
- \( 5.4 \times 10^7 \)
- \( 5.4 \times 10^6 \)
Correct Answer:
B
Explanation
To simplify the expression \( (3 \times 10^4) \times (2 \times 10^3) \) and write it in standard form, let's break it down step-by-step.
### Step 1: Understand the Components
The expression consists of two parts:
- \( 3 \times 10^4 \): This means 3 multiplied by \( 10^4 \) (which is 10,000).
- \( 2 \times 10^3 \): This means 2 multiplied by \( 10^3 \) (which is 1,000).
### Step 2: Apply the Associative Property of Multiplication
We can rearrange and group the terms in the expression:
\[
(3 \times 10^4) \times (2 \times 10^3) = (3 \times 2) \times (10^4 \times 10^3)
\]
### Step 3: Multiply the Coefficients
Now, multiply the coefficients (the numbers in front):
\[
3 \times 2 = 6
\]
### Step 4: Multiply the Powers of Ten
Next, we apply the property of exponents that states \( a^m \times a^n = a^{m+n} \):
\[
10^4 \times 10^3 = 10^{4+3} = 10^7
\]
### Step 5: Combine the Results
Now, we can combine the results from Steps 3 and 4:
\[
(3 \times 10^4) \times (2 \times 10^3) = 6 \times 10^7
\]
### Step 6: Write in Standard Form
The result \( 6 \times 10^7 \) is already in standard form, which is a number between 1 and 10 multiplied by a power of ten.
### Conclusion: Identify the Correct Option
The final simplified expression is \( 6 \times 10^7 \). Therefore, the correct option is:
**A. \( 6 \times 10^7 \)**
### Explanation of Incorrect Options
- **B. \( 6 \times 10^6 \)**: This option is incorrect because it suggests that the power of ten is 6 instead of 7. This would imply a much smaller number (6,000,000) than what we calculated.
- **C. \( 5.4 \times 10^7 \)**: This option is incorrect because it uses a coefficient of 5.4 instead of 6. The multiplication of the coefficients was done correctly, yielding 6.
- **D. \( 5.4 \times 10^6 \)**: This option is incorrect for the same reasons as C; it has both the wrong coefficient and the wrong power of ten.
### Common Pitfalls
- **Forgetting to add the exponents**: When multiplying powers of ten, always remember to add the exponents.
- **Miscalculating the coefficients**: Ensure that you multiply the coefficients correctly; small errors can lead to incorrect answers.
### Revision Summary
- To multiply numbers in scientific notation, multiply the coefficients and add the exponents.
- The result should be expressed in standard form, which is a number between 1 and 10 multiplied by a power of ten.
- Always double-check your calculations for both the coefficients and the powers of ten.
- Familiarize yourself with the properties of exponents to avoid common mistakes.