Hay guys, i really need this formula for my test. the question is.
if u sub n+1= 40, and u sub n-1=10. what is the value of u sub n.

That depends on what is supposed to be. Most likely it refers to some sequence.

If is arithmetic, then each term in the sequence differs by a constant so that

Then

and we find

and so

On the other hand, if is geometric, then consecutive terms are scaled by some constant so that

Then

so there are two possible values for ,

If is some other type of sequence entirely, then this question would be impossible to answer without more information...

11 feet 6 inches and 8 feet 6 inches