# Thread: Find n in the expression below.

1. ## Find n in the expression below.

Ok, I got this expression:

$\displaystyle (\frac{1}{\sqrt2} + 3)^n$
Then I have:
$\displaystyle T_4 = 3\times\sqrt2\times T_3$

Find n.

I got absolutely no idea what $\displaystyle T_3$ and $\displaystyle T_4$ are, so I have no clue how to solve this.

2. ## Re: Find n in the expression below.

Originally Posted by Legjendat
Ok, I got this expression:

$\displaystyle (\frac{1}{\sqrt2} + 3)^n$
Then I have:
$\displaystyle T_4 = 3\times\sqrt2\times T_3$

Find n.

I got absolutely no idea what $\displaystyle T_3$ and $\displaystyle T_4$ are, so I have no clue how to solve this.
Neither do I. What is n supposed to be? What is T supposed to be? What is the actual problem? What context is this in? Even a chapter reference would be good.

-Dan

3. ## Re: Find n in the expression below.

It should be obvious that you can't just put random numbers into an equation and expect that you will always get then same solution. Look back through the problem or area before the problem for references to $\displaystyle T_3$ and $\displaystyle T_4$.

4. ## Re: Find n in the expression below.

Originally Posted by topsquark
Neither do I. What is n supposed to be? What is T supposed to be? What is the actual problem? What context is this in? Even a chapter reference would be good.

-Dan
I swear this is all there was in the question in my exam, and I have never done anything like this before in class, which left me amused.

5. ## Re: Find n in the expression below.

Originally Posted by Legjendat
I swear this is all there was in the question in my exam, and I have never done anything like this before in class, which left me amused.
Well, what course this comes from? Are these Tchebyshev polynomial related questions?

A suggestion, try using binomial expansion