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Simplifying with Nested Parentheses (page 2 of 3)

When you have parentheses inside of parentheses, this is called "nested" parentheses. The process works the same way, but you do need to be a little more careful.

  • Simplify 4[x + 3(2x + 1)]

    When you have nested parentheses like this, the safest plan is to work from the inside out. So I'll take the 3 through the inner parentheses first, before I even think about dealing with the 4 and the brackets. I'll also simplify as I go along. Note that I write each step out completely as I go:

      4[x + 3(2x + 1)]
      4[x + 3(2x) + 3(1)]

      4[x + 6x + 3]

      4[7x + 3]

      4[7x] + 4[3]

      28x + 12

By the way, there is no particular significance to brackets ("[" and "]") versus parentheses versus curly braces ("{" and "}"). Using the different grouping symbols is just a nice way of helping the user keep track of the different pairs of symbols. This is similar to working in an Excel spreadsheet, where the pairs of parentheses in a formula are color-coded, as you can see below:

    Excel screen-shot, showing colored pairs of parentheses

This color-coding helps you see which ")" goes with which "(" in a formula. Using the different types of grouping symbols serves the same purpose in mathematics as the colored parentheses do in the spreadsheet.

FYI: The traditional sequence of grouping symbols, working from the inside out, is "parentheses", then "brackets", and then "braces"; then you repeat the sequence, as necessary. But this is not a rule; it's just a tradition.

  • Simplify 9 – 3[x – (3x + 2)] + 4

    I won't do anything with the "9 –" or the "+ 4" until I simplify inside the brackets and parentheses. I'll work from the inside out:

      9 – 3[x – (3x + 2)] + 4
      9 – 3[x1(3x + 2)] + 4
      9 – 3[x – 1(3x) – 1(2)] + 4
      9 – 3[x – 3x – 2] + 4

      9 – 3[–2x – 2] + 4

      9 – 3[–2x] – 3[–2] + 4

      9 + 6x + 6 + 4

      6x + 19 Copyright © Elizabeth Stapel 2006-2008 All Rights Reserved

It is not required that you write out this many (or this few) steps. You should be careful to do one step at a time, though, writing things out completely and simplifying as you go. You should do as many steps as you need in order to consistently arrive at the correct answer.

  • Simplify 5 + 2{ [3 + (2x – 1) + x] – 2}

    I'll work carefully from the inside out:

      5 + 2{ [3 + (2x – 1) + x] – 2}
      5 + 2{ [3 + 2x – 1 + x] – 2}

      5 + 2{ [2x + x + 3 – 1] – 2}

      5 + 2{ [3x + 2] – 2}

      5 + 2{3x + 2 – 2}

      5 + 2{3x}

      5 + 6x

      6x + 5

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Cite this article as:

Stapel, Elizabeth. "Simplifying with Nested Parentheses." Purplemath. Available from
    http://www.purplemath.com/modules/simparen2.htm. Accessed
 

 

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