Question 287 of 480
Simplify the expression \( 3(x + 4) - 2(2x - 1) \). What is the result?
- \( x + 14 \)
- \( -x + 10 \)
- \( 7 - x \)
- \( 5x + 10 \)
Correct Answer:
B
Explanation
To simplify the expression \( 3(x + 4) - 2(2x - 1) \), we will follow a step-by-step approach.
### Step 1: Distribute the coefficients
First, we need to distribute the numbers outside the parentheses to the terms inside the parentheses.
1. For the first part, \( 3(x + 4) \):
- Multiply \( 3 \) by \( x \): \( 3 \cdot x = 3x \)
- Multiply \( 3 \) by \( 4 \): \( 3 \cdot 4 = 12 \)
- So, \( 3(x + 4) = 3x + 12 \)
2. For the second part, \( -2(2x - 1) \):
- Multiply \( -2 \) by \( 2x \): \( -2 \cdot 2x = -4x \)
- Multiply \( -2 \) by \( -1 \): \( -2 \cdot -1 = 2 \)
- So, \( -2(2x - 1) = -4x + 2 \)
### Step 2: Combine the results
Now we can combine the results from both distributions:
\[
3(x + 4) - 2(2x - 1) = (3x + 12) + (-4x + 2)
\]
This simplifies to:
\[
3x + 12 - 4x + 2
\]
### Step 3: Combine like terms
Next, we will combine the like terms (the terms with \( x \) and the constant terms):
1. Combine the \( x \) terms:
- \( 3x - 4x = -1x \) or simply \( -x \)
2. Combine the constant terms:
- \( 12 + 2 = 14 \)
Putting it all together, we have:
\[
-x + 14
\]
### Final Result
Thus, the simplified expression is:
\[
-x + 14
\]
### Answer Selection
Now, let's look at the options provided:
- A. \( x + 14 \)
- B. \( -x + 10 \)
- C. \( 7 - x \)
- D. \( 5x + 10 \)
The correct answer is not listed among the options provided. The correct simplified expression is \( -x + 14 \), which is not present in the options.
### Explanation of Incorrect Options
- **Option A: \( x + 14 \)**
- This is incorrect because it has the wrong sign for the \( x \) term. The correct term is \( -x \), not \( x \).
- **Option B: \( -x + 10 \)**
- This is incorrect because, while it has the correct sign for the \( x \) term, the constant term is wrong. The correct constant term is \( 14 \), not \( 10 \).
- **Option C: \( 7 - x \)**
- This is incorrect because it has the wrong constant term. The correct constant term is \( 14 \), not \( 7 \).
- **Option D: \( 5x + 10 \)**
- This is incorrect because it has the wrong coefficients for the \( x \) term and the wrong constant term. The correct expression does not have a positive \( 5x \) term.
### Revision Summary
- To simplify expressions, distribute coefficients to terms inside parentheses.
- Combine like terms carefully, ensuring to keep track of signs.
- Always double-check your final expression against the provided options.
- If the correct answer is not among the options, verify your calculations for accuracy.
In this case, the correct simplified expression is \( -x + 14 \).