Question 126 of 480
The slope of the tangent to the curve y = 3x\(^2\) - 2x + 5 at the point (1, 6) is
Correct Answer:
A
Explanation
To find the slope of the tangent to the curve given by the equation \( y = 3x^2 - 2x + 5 \) at the point \( (1, 6) \), we need to follow these steps:
### Step 1: Differentiate the Function
The first step is to find the derivative of the function \( y \) with respect to \( x \). The derivative, denoted as \( \frac{dy}{dx} \), gives us the slope of the tangent line at any point on the curve.
The function is:
\[
y = 3x^2 - 2x + 5
\]
To differentiate, we apply the power rule:
- The derivative of \( 3x^2 \) is \( 6x \) (using \( \frac{d}{dx}(x^n) = nx^{n-1} \)).
- The derivative of \( -2x \) is \( -2 \).
- The derivative of the constant \( 5 \) is \( 0 \).
Putting it all together, we have:
\[
\frac{dy}{dx} = 6x - 2
\]
### Step 2: Evaluate the Derivative at the Given Point
Next, we need to evaluate the derivative at the specific point \( x = 1 \) to find the slope of the tangent line at that point.
Substituting \( x = 1 \) into the derivative:
\[
\frac{dy}{dx} \bigg|_{x=1} = 6(1) - 2 = 6 - 2 = 4
\]
### Conclusion
Thus, the slope of the tangent to the curve at the point \( (1, 6) \) is \( 4 \).
### Answer
The correct option is **A. 4**.
### Explanation of Other Options
- **B. 1**: This option is incorrect because it does not reflect the calculated slope from the derivative. The slope at \( x = 1 \) is \( 4 \), not \( 1 \).
- **C. 6**: This option is also incorrect. While \( 6 \) is the coefficient of \( x^2 \) in the original function, it does not represent the slope at the point \( (1, 6) \).
- **D. 5**: This option is incorrect as well. The value \( 5 \) is the constant term in the function, which does not relate to the slope of the tangent line.
### Common Pitfalls
- **Misunderstanding the Derivative**: Some students may confuse the function value at a point with the slope. Remember, the derivative gives the slope, not the function's output.
- **Forgetting to Substitute**: After finding the derivative, itβs crucial to substitute the correct \( x \) value to find the slope at that specific point.
### Revision Summary
- The slope of the tangent line is found using the derivative of the function.
- Differentiate \( y = 3x^2 - 2x + 5 \) to get \( \frac{dy}{dx} = 6x - 2 \).
- Evaluate the derivative at the point of interest, \( x = 1 \), to find the slope.
- The correct slope at \( (1, 6) \) is \( 4 \), corresponding to option A.