Chapter 29: Problem 5
Differentiate, with respect to \(x\), $$ y=5 x^{4}+4 x-\frac{1}{2 x^{2}}+\frac{1}{\sqrt{x}}-3 $$
Short Answer
Expert verified
The derivative is \(y' = 20x^3 + 4 + \frac{1}{x^3} - \frac{1}{2}x^{-3/2}\).
Step by step solution
01
Apply the Power Rule
Start by differentiating the polynomial terms in the expression: \(5x^4\) and \(4x\). The power rule states that the derivative of \(x^n\) is \(nx^{n-1}\). Thus, the derivative of \(5x^4\) is \(20x^3\) and the derivative of \(4x\) is \(4\).
02
Differentiate the Rational Function
Next, differentiate the term \(-\frac{1}{2x^2}\). Rewrite \(-\frac{1}{2x^2}\) as \(-\frac{1}{2}x^{-2}\) and apply the power rule. The derivative is \(-\frac{1}{2}(-2)x^{-3} = x^{-3} = \frac{1}{x^3}\).
03
Differentiate the Square Root Function
Differentiate the term \(\frac{1}{\sqrt{x}}\). Rewrite \(\frac{1}{\sqrt{x}}\) as \(x^{-1/2}\). Applying the power rule gives \(-\frac{1}{2}x^{-3/2}\) as the derivative.
04
Differentiate the Constant
The derivative of a constant, \(-3\), is \(0\) because constants do not change and therefore have no rate of change.
05
Combine the Derivatives
Combine all the calculated derivatives. The derivative of \(y\) with respect to \(x\) is:\[ y' = 20x^3 + 4 + \frac{1}{x^3} - \frac{1}{2}x^{-3/2}\]
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Power Rule
Differentiation is a fundamental concept in calculus used to find the rate at which a function changes at any point. When differentiating polynomial terms like \(5x^4\) and \(4x\), the power rule is a quick and easy method. The power rule states that if you have a term \(x^n\), its derivative is \(nx^{n-1}\). This means you multiply the exponent by the coefficient and reduce the exponent by one.
- For \(5x^4\), using the power rule, multiply 5 by 4 to get 20 and decrease the exponent 4 by 1, resulting in the derivative \(20x^3\).
- Similarly, the derivative of \(4x\), which is equivalent to \(4x^1\), is simply 4, as subtracting the exponent yields \(4x^0 = 4\).
Polynomial Differentiation
Polynomial differentiation extends the power rule across each term of a polynomial independently. In a polynomial like \(5x^4 + 4x\), apply the power rule to each term one by one. Each term can be differentiated separately because differentiation is linear, meaning the derivative of a sum is the sum of the derivatives.
Applying the power rule to polynomials you encounter in your exercise is systematic and methodical:
Applying the power rule to polynomials you encounter in your exercise is systematic and methodical:
- Identify each term's exponent.
- Apply the power rule to each term separately.
- Combine the resulting derivatives into a single expression.
Rational Function Differentiation
Rational functions, such as terms like \(-\frac{1}{2x^2}\), may appear tricky at first glance. The key is to rewrite these expressions using negative exponents to utilize the power rule effectively. For \(-\frac{1}{2x^2}\), rewrite it as \(-\frac{1}{2}x^{-2}\). Now, you can apply the power rule:
- Multiply the exponent, \(-2\), with the coefficient, \(-\frac{1}{2}\), resulting in 1.
- Decrease the exponent by 1 to get \(-3\), resulting in the derivative \(x^{-3}\).
Square Root Differentiation
Differentiating square roots transforms the problem into a more manageable form using negative fractional exponents. The term \(\frac{1}{\sqrt{x}}\) is equivalent to \(x^{-1/2}\).Apply the power rule to this new expression:
- Multiply the exponent \(-1/2\) by 1 (the coefficient in front), giving \(-1/2\).
- Decrease the original exponent by 1 to obtain \(-3/2\).
- The derivative is therefore \(-\frac{1}{2}x^{-3/2}\).