/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 115 Differentiate each function. $... [FREE SOLUTION] | 91Ó°ÊÓ

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Differentiate each function. $$g(x)=\left(x^{3}-8\right) \cdot \frac{x^{2}+1}{x^{2}-1}$$

Short Answer

Expert verified
Simplify the function, apply the product and quotient rules, combine results, and simplify.

Step by step solution

01

Understand the Problem

Given the function \[g(x)=\frac{(x^{3}-8)(x^{2}+1)}{x^{2}-1}\], we need to find its derivative. We will apply the product rule and quotient rule where necessary.
02

Simplify the Function

Rewrite the function for easier differentiation. Separate it into two parts: \[(x^{3}-8)\] and \[\frac{x^{2}+1}{x^{2}-1}\].
03

Apply the Product Rule

The product rule states \[\frac{d}{dx}[u \times v] = u'v + uv'\], where \[u = x^{3} - 8\] and \[v = \frac{x^{2}+1}{x^{2}-1}\]. First, find the derivatives of both parts separately.
04

Differentiate the First Part

Differentiate \[u = x^{3} - 8\] \to obtain \[u' = 3x^{2}\].
05

Differentiate the Second Part Using the Quotient Rule

The quotient rule states \[\frac{d}{dx}\bigg(\frac{f}{g}\bigg) = \frac{f'g - fg'}{g^2}\], where \[f = x^{2}+1\] and \[g = x^{2}-1\]. Calculate \[f' = 2x\] and \[g' = 2x\], then apply the quotient rule to find \[v'\].
06

Simplify the Quotient Rule Expression

Solve \[v' = \frac{(2x)(x^{2} - 1) - (x^{2}+1)(2x)}{(x^{2} - 1)^2}\]. Simplify this expression.
07

Combine the Results

Combine the differentiated parts using the product rule: \[g'(x) = (3x^{2}) \times \frac{x^{2}+1}{x^{2}-1} + (x^{3} - 8) \times v'\]. Substitute \[v'\] with the simplified expression from the previous step.
08

Final Differentiated Function

Simplify the entire expression to get the final differentiated function.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Product Rule
To differentiate functions that are multiplied together, we apply the product rule. The product rule can be stated as: \[ \frac{d}{dx} [u \times v] = u'v + uv' \]
This means if you have two functions, \( u \) and \( v \), their derivative is found by taking the derivative of the first function (\
Quotient Rule
When differentiating the quotient of two functions, we use the quotient rule:
\[ \frac{d}{dx}\bigg(\frac{f(x)}{g(x)}\bigg) = \frac{f'(x)g(x) - f(x)g'(x)}{[g(x)]^2} \]
This means to find the derivative of a quotient, \(f(x) / g(x)\), you need to:
  • Find the derivative of the numerator, \(f'(x)\).
  • Find the derivative of the denominator, \(g'(x)\).
  • Apply the formula by substituting \(f(x)\), \(g(x)\), \(f'(x)\), and \(g'(x)\) into the quotient rule equation.

In the given exercise, we needed to differentiate the fraction \((x^2 + 1)/(x^2 - 1)\). We started by identifying \( f(x) = x^2 + 1\) and \(g(x) = x^2 - 1\). We then computed their derivatives, \(f'(x) = 2x\) and \(g'(x) = 2x\), respectively. Using the quotient rule, we got:
\[ v' = \frac{(2x)(x^{2} - 1) - (x^{2}+1)(2x)}{(x^{2} - 1)^2} \]
Simplifying this expression provides the derivative needed for further computation.
Derivative Calculation
In the final steps, we use the product and quotient rules to fully differentiate the function. First, identify the parts: \(u = x^3 - 8\) and \(v = \frac{x^2 + 1}{x^2 - 1}\).
We found \(u' = 3x^2\) and applying the quotient rule, worked out \(v' = \frac{(2x)(x^{2} - 1) - (x^{2}+1)(2x)}{(x^{2} - 1)^2}\).
Then, we combined the parts using the product rule:
\[ g'(x) = (3x^2) \times \frac{x^2 + 1}{x^2 - 1} + (x^3 - 8) \times v' \]
Finally, substitute \(v'\) back in and simplify the entire expression to find \(g'(x)\), the desired derivative.

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Most popular questions from this chapter

Let \(f(x)=\frac{x^{2}}{x^{2}-1}\) and \(g(x)=\frac{1}{x^{2}-1}\) a) Compute \(f^{\prime}(x)\) b) Compute \(g^{\prime}(x)\) c) What can you conclude about the graphs of \(f\) and \(g\) on the basis of your results from parts (a) and (b)?

A proof of the Product Rule appears below. Provide a justification for each step. $$\text { a) } \frac{d}{d x}[f(x) \cdot g(x)]=\lim _{h \rightarrow 0} \frac{f(x+h) g(x+h)-f(x) g(x)}{h}$$ $$\text { b) } \quad=\lim _{h \rightarrow 0} \frac{f(x+h) g(x+h)-f(x+h) g(x)+f(x+h) g(x)-f(x) g(x)}{h}$$ $$\text { c) } \quad=\lim _{h \rightarrow 0} \frac{f(x+h) g(x+h)-f(x+h) g(x)}{h}+\lim _{h \rightarrow 0} \frac{f(x+h) g(x)-f(x) g(x)}{h}$$ $$\begin{array}{ll} \text { d) } & =\lim _{h \rightarrow 0}\left[f(x+h) \cdot \frac{g(x+h)-g(x)}{h}\right]+\lim _{h \rightarrow 0}\left[g(x) \cdot \frac{f(x+h)-f(x)}{h}\right] \end{array}$$ $$\text { e) } \quad=f(x) \cdot \lim _{h \rightarrow 0} \frac{g(x+h)-g(x)}{h}+g(x) \cdot \lim _{h \rightarrow 0} \frac{f(x+h)-f(x)}{h}$$ $$\mathbf{f}) \quad=f(x) \cdot g^{\prime}(x)+g(x) \cdot f^{\prime}(x)$$ $$\text { g) } \quad=f(x) \cdot\left[\frac{d}{d x} g(x)\right]+g(x) \cdot\left[\frac{d}{d x} f(x)\right]$$

Find \(d y / d x .\) Each function can be differentiated using the rules developed in this section, but some algebra may be required beforehand. $$y=\frac{x^{5}+x}{x^{2}}$$

Sparkle Pottery has determined that the cost, in dollars, of producing \(x\) vases is given by \(C(x)=4300+2.1 x^{0.6}\) If the revenue from the sale of \(x\) vases is given by \(R(x)=65 x^{0.9},\) find the rate at which the average profit per vase is changing when 50 vases have been made and sold.

For each of the following, graph \(f\) and \(f^{\prime}\) and then determine \(f^{\prime}(1) .\) For Exercises use Deriv on the \(T I-83\). $$f(x)=\frac{5 x^{2}+8 x-3}{3 x^{2}+2}$$

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