R in mathematics stands for set real number set. R+ stands for positive real number and R- stands for negative real number.

Generally speaking, a real number set is a set that usually contains all rational numbers and irrational numbers, and is usually represented by the capital letter R. In the18th century, calculus was developed on the basis of real numbers. But the real number set at that time was not precisely defined.

It was not until 187 1 that German mathematician Cantor put forward the strict definition of real numbers for the first time. Any set that is not empty and has an upper bound (included in R) must have an upper supremum.

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A set of real numbers, including all rational numbers and irrational numbers, is usually represented by the capital letter R.18th century, calculus was developed on the basis of real numbers. But the real number set at that time was not precisely defined. It was not until 187 1 that German mathematician Cantor put forward the strict definition of real numbers for the first time. Any set that is not empty and has an upper bound (included in R) must have an upper supremum.