Sequence Limit (abstract math)

FourierX
Messages
73
Reaction score
0

Homework Statement



If x_n\rightarrow L and y_n \rightarrow M

prove that

x_n - y_n \rightarrow L-M

Homework Equations



Definition of Limit

The Attempt at a Solution



I followed and stayed within the definition of limit of a sequence, but I got 0 for x_n - y_n.
 
Physics news on Phys.org
Can you show us what you did then? Probably your approach is correct but you made a small mistake somewhere.
 
|(x_n- y_n)- (L- M)|= |(x_n- L)+ (-y_n+ M)|\le |x_n-L|+ |-y_n+ M|
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
Back
Top