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Introduction to PEMDAS 6569 Views
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Description:
Please Excuse My Dear Aunt Sally. What did she do? Slander the process of order of operations?
Transcript
- 00:02
In life, order matters. If we didn't pay heed to the natural order
- 00:06
of things, we'd wear our socks over our shoes.
- 00:09
There would be more fist fights than normal at the DMV.
- 00:11
And we'd shower after getting dressed. Algebra is no different. There is a right
- 00:16
and wrong way to do things, and a proper order in which to do them.
Full Transcript
- 00:20
To remember what that order is, we use an acronym called PEMDAS.
- 00:24
It stands for: parentheses, exponents,
- 00:27
multiplication and division, and addition and subtraction.
- 00:32
It does NOT stand for Private Eye Makes District Attorney Sad. But if it helps you remember
- 00:37
the acronym, more power to you. Let's see it in action.
- 00:41
Take the problem 5 - 3 + 6 / 2 + (7 -5) in parentheses - squared.
- 00:50
According to PEMDAS, first we have to take care of those pesky parentheses.
- 00:53
Easy enough. 7 - 5 isn't rocket science. Good thing, or there would be far too many
- 00:59
rocket scientists flooding the job market.
- 01:02
If we rewrite our problem, we get:
- 01:04
5 - 3 + 6 / 2 + 2 squared.
- 01:09
Next we have to rub out any exponents. That fella on the end is the only exponent, so
- 01:14
let's actually square 2 and send him on his way.
- 01:17
Now we've got 5 - 3 + 6 / 2 + 4
- 01:22
There's no multiplication, but we do have a tiny bit of division to perform. 6 / 2
- 01:27
gets our attention first, so says PEMDAS. Yeah, we pretty much do whatever it tells
- 01:32
us to do. We're whipped.
- 01:34
We can rewrite our problem as 5 - 3 + 3 + 4
- 01:39
Addition and subtraction hold equal weight. Subtraction was on the Special K diet for
- 01:43
the past couple of weeks but it didn't take, so we can just perform all remaining operations
- 01:48
from left to right to give us our final answer : 9
- 01:50
Quite a bit different from the answer we'd get if we did everything from left to right
- 01:54
with disregard for procedure. Here, different is not good.
- 01:59
No matter how stylin' you think you look in your shoe-socks.
- 02:02
So there's PEMDAS in a nutshell. Live it. Breathe it. Shmoop it. Love it. Bye.
Up Next
It's impressive that these expressions are able to stay so rational even when they're having operations performed on them.
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