In calculus, understanding the relationship between derivatives and integrals is crucial. The derivative of the natural logarithm function, specifically ln(x), is given by the formula:
$$\frac{d}{dx} \ln(x) = \frac{1}{x}$$
This relationship allows us to derive a corresponding integral rule. By reversing the differentiation process, we can find the integral of 1/x. Thus, the integral can be expressed as:
$$\int \frac{1}{x} \, dx = \ln |x| + C$$
Here, C represents the constant of integration, and the absolute value is included to ensure the function is defined for all values of x, including negative values.
Additionally, 1/x can be rewritten as x-1, which emphasizes that negative exponents indicate reciprocal relationships. This understanding is essential when applying the constant multiple rule in integration.
For example, when integrating 5/x, we can factor out the constant:
$$\int \frac{5}{x} \, dx = 5 \int \frac{1}{x} \, dx = 5 \ln |x| + C$$
Next, consider a more complex integral, such as:
$$\int \left(\frac{1}{x^2} + \frac{3}{x}\right) \, dx$$
This can be separated into two distinct integrals using the sum rule:
$$\int \frac{1}{x^2} \, dx + \int \frac{3}{x} \, dx$$
For the first integral, 1/x2 can be rewritten as x-2. Applying the power rule for integration, we have:
$$\int x^{-2} \, dx = -\frac{1}{x}$$
For the second integral, we again apply the constant multiple rule:
$$\int \frac{3}{x} \, dx = 3 \int \frac{1}{x} \, dx = 3 \ln |x|$$
Combining these results, the final answer for the integral becomes:
$$-\frac{1}{x} + 3 \ln |x| + C$$
Through these examples, we see the application of integration rules, including the power rule and the constant multiple rule, reinforcing the foundational concepts of calculus. Continued practice with various integrals will further enhance understanding and proficiency in this area.