Question: When can parenthesis "go away"?
For example:
(x+15)+(3x-5)=180
The solution is to remove the parenthesis, and solve this:
x+15+3x-5=180
Obviously that is easy to solve. My question is WHY. How do I know when the parenthesis can disappear and when they cannot?
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PEMDAS and Parenthesis
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Here's a free video that might help - https://www.gmatprepnow.com/module/gmat- ... /video/949
NOTE: The part you're interested in starts around 4:00
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Brent
NOTE: The part you're interested in starts around 4:00
Cheers,
Brent
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Hi ntquigley,
One of the standard rules in arithmetic is that you can combine LIKE terms.
When dealing with parentheses, there's often an 'interim' step that you have to go through BEFORE you combine terms.
As an example, I'm going to use your equation and modify it a bit...
(X+15) + 2(3X-5)=180
Notice how the second parenthesis is multiplied by 2. THAT math needs to be done before the like terms are combined...
X + 15 + 6X - 10 = 180
NOW, you can combine like terms:
7X + 5 = 180
7X = 175
X = 25
If you're dealing with parentheses in which you have like terms and no additional 'steps', then you can remove the parenthesis and combine the terms.
GMAT assassins aren't born, they're made,
Rich
One of the standard rules in arithmetic is that you can combine LIKE terms.
When dealing with parentheses, there's often an 'interim' step that you have to go through BEFORE you combine terms.
As an example, I'm going to use your equation and modify it a bit...
(X+15) + 2(3X-5)=180
Notice how the second parenthesis is multiplied by 2. THAT math needs to be done before the like terms are combined...
X + 15 + 6X - 10 = 180
NOW, you can combine like terms:
7X + 5 = 180
7X = 175
X = 25
If you're dealing with parentheses in which you have like terms and no additional 'steps', then you can remove the parenthesis and combine the terms.
GMAT assassins aren't born, they're made,
Rich
