The general rule for integrating a power of is to increase the exponent by one and then divide the term by the new exponent.
Mathematically, this is expressed as:
This rule is valid for any real number except for . When , the denominator becomes zero, making the expression undefined; this specific case requires logarithmic integration.
For terms with a coefficient, such as , the constant remains as a multiplier: .
When a function is differentiated, any constant term (a number without a variable) becomes zero. For example, the derivative of both and is .
Because the original constant is "lost" during differentiation, we must add a constant of integration, denoted as , to the result of an indefinite integral.
This represents the infinite number of possible original functions that could have produced the given derivative.
Before applying the power rule, functions must often be rewritten into the form . This involves using laws of indices to handle fractions and roots.
Negative Indices: Terms in the denominator should be moved to the numerator by changing the sign of the exponent. For example, becomes .
Fractional Indices: Radical signs (roots) must be converted to fractional powers. For example, becomes .
Expansion: If an expression contains brackets or products, it must be fully expanded into individual terms before integrating each term separately.
| Feature | Differentiation | Integration |
|---|---|---|
| Exponent Action | Decrease by 1 | Increase by 1 |
| Coefficient Action | Multiply by old power | Divide by new power |
| Constants | Become zero | Become |
| Result Type | Single gradient function | Family of functions () |
The Differentiation Check: Always verify your integral by differentiating your answer. If you do not arrive back at the original integrand, an error was made in the power or the division.
Check for : In indefinite integration questions, forgetting the constant of integration is a frequent cause of lost marks. Develop a habit of writing immediately after the integration symbol is removed.
Simplify First: Never try to integrate a product or a quotient directly using the power rule. Always simplify the algebra into a sum of separate terms first.
Finding Specific Constants: If a coordinate point is provided, substitute these values into your integrated function to solve for the specific value of .