# Binomial

Discussion in 'Math' started by lomax1, Feb 20, 2014.

1. ### lomax1 Thread Starter New Member

Feb 6, 2014
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Evaluate (0.86)6 to 4 decimal places.

If I punch this into my calculator I get, 0.4045672351 so I should put 40456?

2. ### djsfantasi AAC Fanatic!

Apr 11, 2010
3,496
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A) What does this have to do with a binomial?
B) I assume you didn't mean to imply multiplication.
C) No.

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3. ### DerStrom8 Well-Known Member

Feb 20, 2011
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I see you're trying to get (0.86) to the 6th power. Use a carrot (^) to denote powers. Either that or use a latex editor.

When you're asked to round something to 4 decimal places it means you should have 4 digits to the right of the decimal point. Simple as that.

This is not a binomial.

And as Dj said, what the heck does this have to do with a binomial?

4. ### WBahn Moderator

Mar 31, 2012
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So if someone asked you to write down the value of pi to two decimal places, would you write out 3141?

And since the digit after the 6 in your result is 7, why wouldn't you round up?

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5. ### Lightfire Well-Known Member

Oct 5, 2010
690
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Binomial are two terms (numbers, variables) separated by a plus sign or minus sign.

So x+y is a binomial. (x)(y) x/y are not binomial because there isn't + between the x and y.

6. ### studiot AAC Fanatic!

Nov 9, 2007
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The plus sign is not required, although x+y is a binomial expression, as you say.

7. ### Lightfire Well-Known Member

Oct 5, 2010
690
21
Because x-y is also a binomial?

What do I mean is a plus or minus operation.

8. ### studiot AAC Fanatic!

Nov 9, 2007
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I know you said plus or minus, but I didn't mean that.

The point is that you have to be able to separate the x and the y in an expression so

x/y = -3
x=3y
x+3y=0

Are all equivalent versions of the same binomial expression.

You wished to exclude x/y; xy etc

You do not have to have an equation, either an inequality will also do.

Look at the second part of this:

http://www.algebra.com/algebra/homework/expressions.faq.question.167589.html

9. ### lomax1 Thread Starter New Member

Feb 6, 2014
27
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so, can someone tell me how this will be rounded up?

10. ### DerStrom8 Well-Known Member

Feb 20, 2011
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Not to be rude, but didn't you ever learn this in school?

In order to round to x decimal places you look at the next digit beyond it (to the right). If it's less than 5, then round down, meaning leave the x digit as is. If the next digit is 5 or higher though, you round x up to the next digit.

Example:
Round 63.9548 to 3 decimal places

Look at the 3rd decimal place (4). Then look at the digit beyond it (8). Since 8 is higher than 5, then you need to round x up one digit, so the 4 becomes 5. Therefore, 63.9548 rounded to 3 decimal places is 63.955.

Understand?

11. ### studiot AAC Fanatic!

Nov 9, 2007
5,005
519

Before you learn to round up, what about counting?

You are asked for 4 decimal places, so why are you offering 5?

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12. ### WBahn Moderator

Mar 31, 2012
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From a practical perspective, at least for some situations, you can take the approach of adding a 5 to the first decimal play you want to eliminate and then eliminate that and everything else to the right of it. Using DerStrom8's example should make this clear.

We have 63.9548

We want to round to the 3 decimal places. So we add 0.0005 to the value and get 63.9553. We no just cut off everything to the right of the 3rd place and get 63.955. Now, technically this method (which is exactly the same as DerStrom's classic method that most people learn in elementary or middle school, nothing special about it) injects a tiny bias into the results -- and is therefore called "biased rounding". But my guess is that the bias is too small for you to worry about it any time soon.

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13. ### lomax1 Thread Starter New Member

Feb 6, 2014
27
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I am grateful for your help, however I am not being rude when I say a question is only easy when you know the answer.....

14. ### lomax1 Thread Starter New Member

Feb 6, 2014
27
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Not sure why you are offering anything if you are going to be that rude, apologies I made a mistake.

15. ### WBahn Moderator

Mar 31, 2012
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Would you agree that someone that has not learned (for whatever reason) how to tighten a right-handed nut is probably not at a point where they should be attempting to rebuild an automatic transmission?

Math is the same way. There are layers and layers of skills that, by and large, build upon one another. While there's certainly some flexibility at the margins of what order skills are mastered in, if you get too far ahead of yourself you are likely to hit a brick wall at some point -- hard.

Learning how to round a result to N decimal places fits into one point in the math progression and learning how to exponentiate fits into another. Those two points are far enough apart that someone that hasn't yet learned (for whatever reason) to round a result to N decimal places is almost certainly not properly prepared to master exponentiation. Not because rounding is critical to exponentiation, but because it is an indicator (and not a perfect one, by any means) of where your general level of skill mastery sits.

You yourself gave a big hint to what is likely the underlying problem -- you are just learning to plug numbers into a calculator and taking whatever it spits out. You are not alone. The problem is that this creates, at best, an illusion that you know how to do something and, sooner or later, that illusion will no longer suffice and you will hit a brick wall -- hard.

Sadly, in many schools in many parts of the world (with the so-called "developed" world probably being the worst) the basic skills are seen as "beneath" us (after all, the reasoning goes, we'll never be far from a computer or calculator) and so mastery of them is not expected and many of the skills themselves aren't even presented or, if they are, only in passing. Unfortunately, this means that students are left to deal with mastering them only after they hit that brick wall -- hard enough to bring it to their attention.

16. ### lomax1 Thread Starter New Member

Feb 6, 2014
27
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Unfortunatley I am being taught to pass rather than taught! Sad state of the times. Hence the reason I am staying up to god knows what hour every night trailing forums reading and teaching myself!

17. ### DerStrom8 Well-Known Member

Feb 20, 2011
2,428
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I certainly understand your point, but you seem to have missed mine. Please don't take this the wrong way, I mean no offense, but are you by any chance still in grade school and learning this for the first time? That would make a lot more sense. Most of the members here are used to college-age and up who usually have done this sort of thing many times before. If you are younger, however, I think we all would have a much better understanding of where you are and how to best help you.

Did my post with the example help?

Regards,
Matt

18. ### WBahn Moderator

Mar 31, 2012
20,239
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Yes, sad times and it's not an easy road to travel -- so hat's off to you for making the effort (when most don't).

But, as DerStrom8 has indicated, we would be in a much better position to tailor our help if we have a better understanding of where you are in your educational journey. What is reasonable to expect of a twenty-something and what is reasonable to expect of a pre-teen are very different. It's not the end-all be-all, but it gives us a useful context to start from.

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