Chapter 3: Problem 20
Find the slope of the curve at the point indicated. \(y=x^{3}-2 x+7, \quad x=-2\)
Short Answer
Expert verified
The slope of the curve at \( x = -2 \) is 10.
Step by step solution
01
Differentiate the Function
To find the slope of the curve at a given point, we need to find the derivative of the function.The function is given as \( y = x^3 - 2x + 7 \).The derivative of \( y \), denoted as \( y' \) or \( \frac{dy}{dx} \), with respect to \( x \), is:\[ \frac{dy}{dx} = 3x^2 - 2 \].
02
Evaluate the Derivative at the Given Point
Now that we have the derivative, we need to evaluate it at \( x = -2 \) to find the slope of the curve at this point.Substitute \( x = -2 \) into the derivative:\[ \frac{dy}{dx}(-2) = 3(-2)^2 - 2 \].Calculate:\[ 3(4) - 2 = 12 - 2 = 10 \].
03
Interpret the Result
The value \( 10 \) we calculated in Step 2 is the slope of the curve at the point where \( x = -2 \). This means that at this point, the curve rises 10 units for every unit it moves to the right.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Derivative
A derivative represents the rate at which a function changes at any given point. In simple terms, it tells us how steep a curve is at a specific location. The mathematical symbolism for a derivative is often written as \( f'(x) \) or \( \frac{dy}{dx} \). Derivatives are central to calculus as they allow you to compute slopes of
- linear equations, which are constant slopes, and
- non-linear equations, where the slope might vary from one point to another.
Slope of a Curve
Visualizing the slope of a curve can be compared to the concept of a tangent touching a curve at a single point. Imagine standing on a hill; the gradient of the hill at your location is akin to the slope of a curve at that point. The slope tells us
- whether the curve is increasing or decreasing, and
- how quickly, quantified by the numerical value of the slope.
Differentiation
Differentiation is the mathematical process of finding a derivative. When you differentiate a function, you essentially determine how the function changes with respect to its variable. For polynomials, this often involves applying the power rule, where:
- The derivative of \( x^n \) is \( nx^{n-1} \).
Evaluate Derivative
Evaluating a derivative involves substituting a specific value into the derivative function to calculate the slope at that point. This step bridges the abstract derivative concept to practical application. For instance, by substituting \( x = -2 \) into \( \frac{dy}{dx} = 3x^2 - 2 \), you compute
- \( 3(-2)^2 - 2 = 12 - 2 = 10 \).
Polynomial Function
Polynomial functions are expressions composed of variables raised to whole-number exponents. These are some of the simplest types of functions to differentiate. Consider the equation \( y = x^3 - 2x + 7 \).
- The degree of this polynomial is 3, determined by the highest exponent, which is often reflective of the curve's complexity.
- Polynomial derivatives frequently diminish in degree by one, simplifying the function while revealing critical details about its slope at various points.