Math Is Fun Forum

Chris2010

Guest

letter in lower right hand corner.

The problem I am working with is "a" and then an "n" in the lower right hand corner. I know in the upper right hand corner that means to the nth power, but what does an "n" mean when it is in the lower right hand corner?

Would look like

a
  n

Something close to that.

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: letter in lower right hand corner.

Hi Chris2010;

Welcome to the forum!

The n is called a subscript.

can be used as a variable such as

It can represent a recurrence realtion:

You can see the use of subscripts heavily in hypergeometric functions,Tensor analysis or Matrix theory.
But basically it is a variable with an index. Like this:

Would mean you have:

You can go to infinity:

Would mean you have:

Can be used liike a loop variable because when you say:

Would mean you have:

Now you can use them in calculations:

Only scratched the surface of what you can with an indexed variable.

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Chris2010

Guest

Re: letter in lower right hand corner.

Ok, thank you, but how do you figure out 'a subscript n?'

You have a subscript n = 10, well how would a subscript n turn out to be 10? What numbers would a and n be and how would you put them together to get 10? Do you work it like you do 'to the power of' or do you just multiply a and n or what?

That is what is really confusing me.

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: letter in lower right hand corner.

Hi Chris2010;

Please reread my post above I added some things.

When you say

That was an assignment, like d = 12. It means

equals 5. No operation is performed. It is not like

Which means a*a. It is really just a flexible and convenient way of writing variables.

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Chris2010

Guest

Re: letter in lower right hand corner.

I don't see the point of using

if it is just to basically say it is a certain number and no equation is done.

Because the problem I was working on was

It's not letting me do it, but it is 'a subscript 40' = whatever the problem was = 4840

I don't see the point of having to include the 'a subscript 40' if you don't do anything with it. Seems pointless and that it is there just to confuse.

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: letter in lower right hand corner.

Hi;

I don't see the point of having to include the 'a subscript 40' if you don't do anything with it. Seems pointless and that it is there just to confuse.

Some people do use unnecessary notations to confuse people. But that is not the case with a subscripted or indexed variable. Supposing I wanted 400 variables that all equaled 9.

I could say:

Now

All equal 9. Now how much work would that be without subscripted variables!

I could start a = 9 , b = 9, c = 9, but what happens after z. I run out of variable names. It is sort of like using numbers for street names. I can have 38 th st. I could have 123 avenue. More flexible and more variables.

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Chris2010

Guest

Re: letter in lower right hand corner.

So you are never to figure out what a stands for, you are just given a number and a equals that no math needed it just equals that no questions asked. Thank you.

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: letter in lower right hand corner.

Hi;

Like with any other variable we do pick names that help us remember what they stand for. When you get to computer programming this will all make much more sense. In the meantime do not panic when you see them.

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.