In calculus, an integral rule refers to a formula or technique used to evaluate definite or indefinite integrals. There are several integral rules, each designed to solve different types of integrals.

Some common integral rules include:

• Power rule: This rule applies to integrals of the form ∫x^n dx, where n is any real number except for -1. The power rule states that ∫x^n dx = (1/(n+1))x^(n+1) + C, where C is the constant of integration.
• Substitution rule: This rule is used to simplify integrals by substituting one variable with another. The substitution rule states that if u = g(x), then ∫f(g(x))g'(x) dx = ∫f(u) du.
• Integration by parts: This rule is used to integrate the product of two functions. The integration by parts formula states that ∫u dv = uv - ∫v du, where u and v are functions of x and du/dx and dv/dx are their respective derivatives.
• Trigonometric substitution: This rule is used to integrate functions that involve trigonometric functions. It involves substituting a trigonometric expression for x in the integral.
• Partial fractions: This rule is used to simplify integrals that involve rational functions. It involves breaking the rational function into simpler fractions.

Integral rules are an essential tool in calculus, and they are used to solve a wide variety of problems in physics, engineering, economics, and other fields.