Problem 7 - Calculus Early Transcendentals

Question

Find the derivative of the following functions. $$y=x^{5}$$

Step-by-Step Solution

Answer

Answer: The derivative of the function $$y=x^5$$ is $$\frac{dy}{dx} = 5x^{4}$$.

Step 1: Apply the power rule

To find the derivative of $$y = x^5$$, we will apply the power rule, which states that if $$y = x^n$$, then $$\frac{dy}{dx} = nx^{n-1}$$. In this case, n = 5.

Step 2: Find the derivative

Applying the power rule to $$y = x^5$$, we get: $$\frac{dy}{dx} = 5x^{5-1}$$

Step 3: Simplify the expression

Now we simplify the expression: $$\frac{dy}{dx} = 5x^{4}$$ So the derivative of the function $$y=x^5$$ is $$\frac{dy}{dx} = 5x^{4}$$.

Key Concepts

Power Rule in Calculus

Understanding the power rule in calculus is fundamental when dealing with polynomial functions. It is a quick way to find the derivative of a function where the variable has an exponent, or 'power.' In essence, the power rule states that for a function in the form of f(x) = x^n, where n is a real number, the derivative f'(x) will be nx^{n-1}.

Let's see why this works. It’s actually based on the limit definition of a derivative where the exponents decrease by one and get multiplied by the original exponent through a process of increment and evaluation. This elegantly captures the nature of change for power functions.

Applying the Power Rule

To apply the power rule effectively, identify the exponent (n) of the function. Then, bring the exponent down in front of the variable, which now becomes (n-1) instead as its new exponent. For example, if your function is y=x^5, then its derivative is 5x^4, as the exponent 5 is brought down and the power reduced by 1.

Derivative of Polynomial Functions

Polynomial functions are sums of power functions, like f(x) = a_nx^n + a_{n-1}x^{n-1} + ... + a_2x^2 + a_1x + a_0, where the a_i values are coefficients and x is raised to nonnegative integer powers. To find the derivative of a polynomial function, you go term by term, applying our trusty power rule to each component of the polynomial.

Working Through Each Term

Begin with the highest degree of x and work your way down to the lowest. Each term's derivative will be found separately, using the power rule, and then you combine them to find the complete derivative of the function. Remember to apply the constant factor rule as well, which says that the derivative of a constant times a function is the constant times the derivative of the function. This is particularly handy when dealing with the coefficients of our polynomial terms.

Simplifying Mathematical Expressions

Once you've applied the power rule to find the derivatives of polynomial functions, it's important to simplify the expressions to make them as clear and concise as possible. Simplification may involve combining like terms, reducing fractions, or factoring. The aim is to remove any mathematical clutter, leaving a neat result that's easier to read and understand.

Tips for Simplification

Simplifying expressions often includes eliminating any terms that have a coefficient of zero or combining terms that have the same power of x. When simplifying derivatives of polynomials, be on the lookout for exponents that drop to zero - remember, any nonzero number to the power of zero is just one.

Also, don't forget to express your final answers in decreasing powers of x, which is the standard form for polynomials. It's not just about finding the derivative; presenting it well is part of good mathematical practice!