Compute lim as n tends to infinity of f(xn)

  • Thread starter Thread starter Anne5632
  • Start date Start date
  • Tags Tags
    Infinity
Click For Summary
The discussion centers on computing the limit of the function f(xn) as n approaches infinity, where f(x) is defined piecewise. The sequence xn is given as -1/n, which approaches zero as n increases. Participants clarify that for n > 0, xn is negative, leading to the evaluation of f(xn) as x - 1, resulting in a limit of -1. The conversation emphasizes the importance of determining whether to compute the limit of f(xn) or f(lim xn). Ultimately, the limit of f(xn) as n tends to infinity is -1.
Anne5632
Messages
23
Reaction score
2
Homework Statement
Compute the lim of f(xn)
Relevant Equations
Let f(X) =X if X>=0
And f(X)= x-1 if X<0
Let Xn = -1/n
As n tends to inf, the fraction goes to zero so would the lim just be X?
 
Physics news on Phys.org
Anne5632 said:
Homework Statement:: Compute the lim of f(xn)
Relevant Equations:: Let f(X) =X if X>=0
And f(X)= x-1 if X<0
Let Xn = -1/n

As n tends to inf, the fraction goes to zero so would the lim just be X?
Do you want to calculate:$$\lim_{n \rightarrow \infty}f(x_n)$$or$$f(\lim_{n \rightarrow \infty}x_n)$$
 
PeroK said:
Do you want to calculate:$$\lim_{n \rightarrow \infty}f(x_n)$$or$$f(\lim_{n \rightarrow \infty}x_n)$$
First one
 
Anne5632 said:
First one
Can you write out the sequence ##f(x_n)##?
 
-1, -1/2,-1/3,-1/4...
 
Anne5632 said:
-1, -1/2,-1/3,-1/4...
That's ##x_n## isn't it?
 
What's ##f(x_1)## for example?
 
PeroK said:
What's ##f(x_1)## for example?
-1?
 
Anne5632 said:
-1?
It's ##-2##, isn't it?
 
  • Like
Likes pbuk
  • #10
Anne5632 said:
As n tends to inf, the fraction goes to zero so would the lim just be X?
If you start with ##n>0##, what would the comparison relation between ##-(1/n)## and ##0## be?