# Bracket ([])

Pronunciation: /ˈbɹæk.ɪt/ Explain

Brackets are marks used to group operations and mark the beginning and end of matrices. Brackets are usually used in pairs. The left bracket looks like: [. The right bracket looks like: ].

Brackets are most often used to mark the beginning and end of matrices. For example: A = [ 5 -1 2 ].

Brackets are occasionally used to group operations in arithmetic, usually along with parentheses. For example, the expression 5·4+2 evaluates to 22. Using the order of operations, we first multiply 5 and 4 to get 20, and then add 2 to get 22.

However, if we use brackets write the expression as 5·[4+2], the value of the expression changes. The bracket tells us to add 4 to 2 before multiplying by 5. Adding 4 and 2 gives us 6. When we then multiply by 5 we get 30.

### References

1. McAdams, David E.. All Math Words Dictionary, bracket. 2nd Classroom edition 20150108-4799968. pg 28. Life is a Story Problem LLC. January 8, 2015. Buy the book

McAdams, David E. Bracket ([]). 4/12/2019. All Math Words Encyclopedia. Life is a Story Problem LLC. http://www.allmathwords.org/en/b/bracket.html.

### Revision History

4/12/2019: Changed equations and expressions to new format. (McAdams, David E.)
1/29/2019: Changed 'always' to 'usually'. (McAdams, David E.)
12/21/2018: Reviewed and corrected IPA pronunication. (McAdams, David E.)