Chapter 5: Problem 5
Find the derivative and state a corresponding integration formula. $$ \frac{d}{d x}[\sqrt{x^{3}+5}] $$
Short Answer
Expert verified
The derivative is \( \frac{3x^2}{2\sqrt{x^3+5}} \) and the corresponding integration formula is \( \int \frac{3x^2}{2\sqrt{x^3+5}} \, dx = \sqrt{x^3+5} + C \).
Step by step solution
01
Identify the Function
The function we need to differentiate is \( f(x) = \sqrt{x^3 + 5} \). This can also be written as \( (x^3 + 5)^{1/2} \). It is a composition of functions: an outer function (the square root) and an inner function \( x^3 + 5 \).
02
Apply the Chain Rule
To differentiate \( f(x) = (x^3 + 5)^{1/2} \), we use the chain rule. The chain rule states that the derivative \( \frac{d}{dx}[u(v)] = u'(v) \cdot v'(x) \). Here, \( u(v) = v^{1/2} \) and \( v = x^3 + 5 \), so \( u'(v) = \frac{1}{2}v^{-1/2} \) and \( v'(x) = 3x^2 \).
03
Differentiate the Outer Function
First, differentiate the outer function \( u(v) = v^{1/2} \) with respect to \( v \), which gives: \( u'(v) = \frac{1}{2} v^{-1/2} \).
04
Differentiate the Inner Function
Next, differentiate the inner function \( v(x) = x^3 + 5 \) with respect to \( x \), which results in: \( v'(x) = 3x^2 \).
05
Combine Using the Chain Rule
Combine the derivatives from the previous steps using the chain rule: \( \frac{d}{dx}[(x^3+5)^{1/2}] = \frac{1}{2}(x^3+5)^{-1/2} \cdot 3x^2 = \frac{3x^2}{2\sqrt{x^3+5}} \).
06
State a Corresponding Integration Formula
The derivative we found is \( \frac{3x^2}{2\sqrt{x^3+5}} \). To find a corresponding integration formula, recognize that differentiating \( \sqrt{x^3+5} \) gave us this result. Thus, if you integrate \( \frac{3x^2}{2\sqrt{x^3+5}} \) with respect to \( x \), you would obtain \( \sqrt{x^3+5} + C \) where \( C \) is the constant of integration.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Chain Rule
The chain rule is a fundamental principle in calculus used for differentiating composite functions. A composite function is essentially a function made up of other functions, just like the one in our exercise: \( f(x) = (x^3 + 5)^{1/2} \). Understanding the chain rule allows us to break down complex functions into simpler parts for easier differentiation.
- Think of the chain rule like peeling an onion layer by layer. You start from the outside and work your way inward.
- The rule itself states that to differentiate a composite function \( f(g(x)) \), you multiply the derivative of the outer function \( f \) by the derivative of the inner function \( g \). Mathematically, it's expressed as \( \frac{d}{dx}[f(g(x))] = f'(g(x)) \cdot g'(x) \).
- In our problem, the outer function is the square root, expressed as \( (v)^{1/2} \), and the inner function is \( x^3 + 5 \).
Function Composition
Function composition is the process of combining two functions to form a new one. It is represented as \( (f \circ g)(x) = f(g(x)) \), meaning you apply one function to the results of another.
- In our exercise, the function \( f(x) = \sqrt{x^3 + 5} \) is composed of an outer square root function and an inner polynomial function \( x^3 + 5 \).
- This creates a connection between the functions, where the output of the inner function (\( x^3 + 5 \)) is used as the input for the outer function (the square root).
Integration Formula
Once you've differentiated a function, it's often useful to find the corresponding integration formula.
- Integration essentially reverses differentiation. If you know the derivative, you can obtain the original function through integration, plus a constant term \( C \), known as the constant of integration.
- In our problem, after finding the derivative \( \frac{3x^2}{2\sqrt{x^3+5}} \), we state the corresponding integration formula as \( \int \frac{3x^2}{2\sqrt{x^3+5}} \, dx = \sqrt{x^3 + 5} + C \).
- This relationship showcases the beautiful connection between differentiation and integration, often referred to as the "Fundamental Theorem of Calculus".