Which symbol is commonly used to denote an integral?

The symbol commonly used to denote an integral is indeed ∫. This symbol is derived from the Latin word "summa," which emphasizes the concept of integration as a summation of infinitesimally small parts over an interval. When we compute an integral, we are essentially finding the area under a curve or the accumulation of quantities over a certain range.

In calculus, this is central to understanding both definite and indefinite integrals, where ∫ indicates the operation of taking the integral of a function. The integral symbol is a fundamental notation that permeates various applications in mathematics, physics, and engineering, highlighting its significance in both theoretical and practical applications.

The other symbols mentioned serve different purposes in mathematics: ∑ represents summation, often used in series and sequences; ∂ indicates partial derivatives, critical in multivariable calculus; and Δ is typically used to signify change or difference, such as in the context of limits or differences in variables. Each of these has its distinct role, but none are used to denote integration.