What do these [] brackets signify?

Question

to a question i asked here:

http://answers.yahoo.com/question/index;_ylt=AukywVZKBztrwrpe6z3ctZTsy6IX;_ylv=3?qid=20080901075211AAZEwe7

the answerer stated:

S = A*[(1+i)^n - 1]/i

what do the brackets [] signify? how do they differ from ()?

This factor is known as F/A(i,n) if you want to reference it.

This is found in most financial or accounting textbooks/resources.

Answer 1

In the context of that question, parentheses ( ), brackets [ ] and braces { } are all be equivalent.

People use a variety of shapes in complex formulae because it makes the formulae easier to read, and facilitates checking that there is a close bracket matching every open bracket.

In other contexts in mathematics, the different shapes can have a variety of meanings. Here is one example for brackets of each shape.

( ) are used to specify the endpoints of open intervals:

(4, 7) means all values of x such that 4 < x < 7.

[ ] are used to specify the endpoints of closed intervals:

[4, 7] means all values of x such that 4 <= x <= 7.

{ } are used to enclose items in a set:

{ 3, 15, 17 } means the set containing the numbers 3, 15 and 17.