when to use ()

bobisaka

Junior Member
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Dec 25, 2019
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For the example below , I have used brackets to get.. 18(4/3) = 72/3 Which is incorrect in the example solution.

1580255386012.png

In general, when should i use brackets?

How do I know when to use brackets and not to use it?

Is it because i have to multply it identically as the opposite side of the equations(did not use brackets)?










 

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For the example below , I have used brackets to get.. 18(4/3) = 72/3 Which is incorrect in the example solution.

View attachment 16336

In general, when should i use brackets?

How do I know when to use brackets and not to use it?

Is it because i have to multply it identically as the opposite side of the equations(did not use brackets)?
Looks like you did NOT post the "complete" problem.

As posted your work is correct - you did not need to use bracket.
 
Hi bobisaka. You didn't finish simplifying your result.

72/3 = 24

because

3 × 24 = 72

Note: If you cancel common factors before multiplying, then you don't need to reduce 72/3 to lowest terms (i.e., 3 goes into 18 six times).

\(\displaystyle \displaystyle \dfrac{4}{3} × \dfrac{18}{1} \;\; = \;\; \dfrac{4}{\cancel{3}_{1}} × \dfrac{\cancel{18}^{6}}{1} \;\; = \;\; \dfrac{4×6}{1×1} \; = \; \dfrac{24}{1} \; = \; 24\)

I'm not sure about your question concerning brackets. Using grouping symbols is just one way to show multiplication.

?
 
Here's what I noticed:
Your answer of 72/3 is correct, just not in the correct form. 72/3 is 24, when simplified.
Brackets are generally used to group multiple sets of parenthesis together, but parenthesis apply to grouping individual numbers or an expression for the use of PEMDAS (Parenthesis, Exponent, Multiply/Divide, and Add/Subtract) or to imply a group of numbers (if directly next to the implied) being multiplied by the touching number or set of parenthesis.
E.G. (3+4)/7=1, which is the same as 7/7; or in the case of (3x-4)(4x+3), which is the same as (3x+4) * (4x+3).
Brackets would be used in an instance like this: [3*(3-9)/5 - (4x +6)] - 5.
I hope this answers your question!
 
If you want to multiply a sum or difference by some number then you will need parenthesis.

For example, if you want to denote that you want to multiply the sum of 4 and 5 by 7, then you would write 7(4+5)

Is this what you are looking for?
 
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