What it means
An elongated S, for sum: the integral adds up infinitely many infinitely thin pieces. With limits it gives a number, such as an area under a curve; without limits it means an antiderivative. The dx at the end names the variable. ∬ is a double integral and ∮ an integral around a closed path.
Read aloud in real formulas
∫₀¹ x² dx = 1/3
Aethel says
the integral from zero to one of x squared d x equals 1 over 3
the area under x squared from 0 to 1
∫₋∞^∞ f(x) dx = 1
Aethel says
the integral from negative infinity to infinity of f of x, d x equals 1
a probability density integrates to one
Typing it
- LaTeX
- \int_a^b, \iint, \oint
- Unicode
- U+222B
Formulas that use it
Questions
How do you say ∫ out loud?
It is usually read “the integral from a to b of”, and also “the integral of”.
What does ∫ mean in maths?
An elongated S, for sum: the integral adds up infinitely many infinitely thin pieces. With limits it gives a number, such as an area under a curve; without limits it means an antiderivative. The dx at the end names the variable. ∬ is a double integral and ∮ an integral around a closed path.
How do you type ∫?
In LaTeX, write \int_a^b, \iint, \oint. Its Unicode code point is U+222B.