Chapter 13: Problem 8
Find the slope of the tangent line to each curve when \(x\) has the given value. Do not use a calculator. $$f(x)=6 x^{2}-4 x, x=-1$$
Short Answer
Expert verified
The slope of the tangent line is \(-16\).
Step by step solution
01
Understand the Problem
We need to find the slope of the tangent line to the curve represented by the function \( f(x) = 6x^2 - 4x \) at the point where \( x = -1 \). This involves finding the derivative of the function and evaluating it at \( x = -1 \).
02
Find the Derivative
The slope of the tangent line at a given point on the curve is the value of the derivative of the function at that point. Let's find \( f'(x) \), the derivative of \( f(x) = 6x^2 - 4x \).Using the power rule, the derivative of \( f(x) \) is calculated as follows:\[ f'(x) = \frac{d}{dx}(6x^2) - \frac{d}{dx}(4x) \]Thus,\[ f'(x) = 12x - 4 \].
03
Evaluate the Derivative at \( x = -1 \)
Now that we have \( f'(x) = 12x - 4 \), we will substitute \( x = -1 \) to find the slope of the tangent line.\[ f'(-1) = 12(-1) - 4 \].Calculate \[ f'(-1) = -12 - 4 = -16 \].
04
Conclude the Solution
The slope of the tangent line to the curve \( f(x) = 6x^2 - 4x \) at \( x = -1 \) is \(-16\). This means the line is decreasing steeply at that point on the curve.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Slope of a Curve
When we talk about the slope of a curve at a specific point, we are essentially referring to the steepness or incline of the curve at that point. Unlike straight lines that have a constant slope, curves can have different slopes at different points. This varying slope is because the shape of the curve changes continuously.
To find the slope of a curve at a particular point, we determine the slope of the tangent line to the curve at that point. The tangent line is a straight line that just "touches" the curve at the point of interest and has the same slope as the curve there.
To find the slope of a curve at a particular point, we determine the slope of the tangent line to the curve at that point. The tangent line is a straight line that just "touches" the curve at the point of interest and has the same slope as the curve there.
- The slope of the curve at a point gives us an idea of how the curve behaves at that exact location.
- A positive slope means the curve is rising, while a negative slope indicates it is falling.
Derivative of a Function
The derivative of a function is a cornerstone concept in calculus. It measures how the function's output changes concerning its input. In simpler terms, it tells us how a tiny change in the input affects the function's output.
A derivative at a specific point gives us the slope of the tangent line to the curve at that point.
When we compute the derivative of a function like \( f(x) = 6x^2 - 4x \), we find an expression for \( f'(x) \) that can give the slope of the tangent for any value of \( x \).
A derivative at a specific point gives us the slope of the tangent line to the curve at that point.
When we compute the derivative of a function like \( f(x) = 6x^2 - 4x \), we find an expression for \( f'(x) \) that can give the slope of the tangent for any value of \( x \).
- The derivative is often denoted as \( f'(x) \) or \( \frac{df}{dx} \).
- Finding the derivative is essential for identifying how a variable quantity changes over time.
Power Rule in Calculus
In calculus, the power rule is a basic tool used to find the derivative of functions involving exponents. It simplifies the process of differentiation considerably and is applicable to any function of the form \( x^n \), where \( n \) is a real number.
The power rule states that if you have a function \( f(x) = x^n \), its derivative \( f'(x) \) is \( nx^{n-1} \). The power gets multiplied by the coefficient, and then you reduce the power by one.
The power rule states that if you have a function \( f(x) = x^n \), its derivative \( f'(x) \) is \( nx^{n-1} \). The power gets multiplied by the coefficient, and then you reduce the power by one.
- For example, if \( f(x) = 6x^2 \), then according to the power rule, \( f'(x) = 2 \cdot 6x^{2-1} = 12x \).
- This method dramatically reduces the complexity of taking derivatives and is one of the first rules of differentiation that students learn.