Problem 26 - Applied Mathematics: For the Managerial, Life, and Social Sciences

Question

Find the derivative of each function. \(f(x)=\frac{x+1}{2 x^{2}+2 x+3}\)

Step-by-Step Solution

Answer

The derivative of the given function is: \(f'(x) = \frac{-2x^2 - 4x + 1}{(2x^2 + 2x + 3)^2}\).

Step 1: Identify the Parts of the Function and Find Derivatives

Identify the parts of the function that represent the numerator and the denominator. In this case, \(f(x) = x+1\) and \(h(x) = 2x^2 + 2x +3\). Then, find the derivatives of each part. The derivative of \(f(x) = x + 1\) is: \(f'(x) = 1\). The derivative of \(h(x) = 2x^2 + 2x + 3\) is: \(h'(x) = 4x + 2\).

Step 2: Apply the Quotient Rule

Now, we can use the quotient rule to find the derivative of the function: \[g'(x) = \frac{h(x)f'(x) - f(x)h'(x)}{[h(x)]^2}\] Plugging in the functions and their derivatives that we found in step 1, we get: \[f'(x) = \frac{(2x^2 + 2x +3)(1) - (x+1)(4x+2)}{(2x^2 + 2x + 3)^2}\]

Step 3: Simplify the Expression

Finally, we can simplify the expression to find the derivative: \[f'(x) = \frac{2x^2 + 2x + 3 - 4x^2 - 2x - 4x - 2}{(2x^2 + 2x + 3)^2}\] Combining like terms in the numerator: \[f'(x) = \frac{-2x^2 - 4x + 1}{(2x^2 + 2x + 3)^2}\] Therefore, the derivative of the given function is: \(f'(x) = \frac{-2x^2 - 4x + 1}{(2x^2 + 2x + 3)^2}\)

Key Concepts

Quotient Rule

The quotient rule is a technique in calculus used to differentiate functions that are given as fractions, more precisely a quotient involving two functions. This rule is essential whenever you encounter derivatives of a function that is the division of two other functions.

Consider a function of the form \( \frac{f(x)}{g(x)} \). The quotient rule provides a structured way to find the derivative of such a function.

The formula for the quotient rule is:

• \(\left(\frac{f}{g}\right)'(x) = \frac{g(x)f'(x) - f(x)g'(x)}{[g(x)]^2}\)

This means you first differentiate the numerator and the denominator separately. The key is to keep the structure: multiply the derivative of the numerator by the original denominator, and subtract the product of the original numerator and the derivative of the denominator. Don't forget to square the denominator for the final term!

Remember, the order is important in subtraction within the numerator, so ensure that you apply this part carefully. This formula helps us tackle derivative calculus problems involving division.

Function Differentiation

Function differentiation is the process of finding a derivative of a function. A derivative represents how a function changes as its inputs change – in other words, the rate of change or slope at any given point.

Differentiation is a fundamental concept in calculus and is applied using basic rules like the product rule, chain rule, sum rule, and the quotient rule. Each of these rules aids in differentiating different types of functions.

In the context of our exercise, differentiation dealt with finding derivatives for both parts of our quotient function:

• The numerator \( f(x) = x + 1 \) which becomes \( f'(x) = 1 \),
• The denominator \( h(x) = 2x^2 + 2x + 3 \) which transforms into \( h'(x) = 4x + 2 \).

Understanding how each part of a function transforms through differentiation enables you to solve calculus problems by constructing and manipulating derivatives accurately.

Calculus Problems

Calculus problems can often appear challenging due to their reliance on various fundamental concepts and rules. However, if you approach them methodically, they can become much easier to manage.

Solving calculus problems often involves multiple steps, such as:

• Identifying the type of problem and the correct rule to apply (e.g., applying the quotient rule for fractions),
• Carefully differentiating the involved functions,
• Substituting these derivatives into a broader formula, and then
• Simplifying to find the final expression.

In the problem at hand, using the quotient rule to differentiate \( \frac{x+1}{2x^2+2x+3} \), helped deconstruct the problem:

• First, derivation of the separate parts using function differentiation
• Application of the quotient rule formula correctly,
• Simplification to reach the final derivative form \( \frac{-2x^2 - 4x + 1}{(2x^2 + 2x + 3)^2} \).

Step-by-step problem-solving in calculus, focusing on details and transformations, allows a learner to conquer complex calculus quizzes and assignments with confidence.