Return Styles: Pseud0ch, Terminal, Valhalla, NES, Geocities, Blue Moon. Entire thread

Solve Please

Name: Anonymous 2008-08-13 18:05

lim(n->INF)

  n^2+1
----------
(n+1)^2+1

The mark scheme says it equals 1. But I also get a remainder of -2n-1.

What am I doing wrong?

Name: Anonymous 2008-08-13 18:08

for neatness:
n^2 + 1
----------
(n+1)^2 +1

lim(n->INF)

Name: Apollo 2008-08-13 18:10

divide top and botton by n

n + 1/n
-------
n + 2 +2/n

apply limits

INF + 0
--------        ~ 1
INF + 2 + 0

Name: Anonymous 2008-08-13 18:14

n^2+1

n^2+2n+2

              1
            ------------
n^2+2n+2  :  n^2     +1
            ------------
            -n^2 -2n -2
            ------------
                 -2n -1

You're right...mark scheme's wrong.

Name: Anonymous 2008-08-13 18:21

You can't apply limits like that...lim(n->inf) just means there is no limit.

Name: Anonymous 2008-08-13 21:07

>>5
yes you can, and the marking scheme's right.

(n^2+1)/((n+1)^2+1) = (1+1/n^2)/(1+2/n+2/n^2)
take lim(n->infinity) and you get 1 (1/n etc tend to 0)

Name: Anonymous 2008-08-13 21:35

abstract nonsense.

Name: Anonymous 2008-08-14 0:30

this thread needs some tex

\lim_{n\to \infty}\frac{n^2+1}{(n+1)^2+1} = \lim_{n\to \infty}\frac{n^2+1}{n^2+2n+2}
=\lim_{n\to \infty}1 -\frac{2n+1}{n^2+2n+2} = \lim_{n\to \infty}1 -\frac{2+1/n}{n+2+2/n} = 1 + 0

or

\lim_{n\to \infty}\frac{n^2+1}{(n+1)^2+1} = \lim_{n\to \infty}\frac{n^2+1}{n^2+2n+2}
=\lim_{n\to \infty}\frac{1+1/n^2}{1+2/n+2/n^2} = \frac{1+0}{1+0+0}

Name: Anonymous 2008-08-14 10:55

It's pretty obviously 1.

>>8

shows a pretty mathematically sound argument, but merely by observing that it's the quotient of two monic polynomials of the same degree shows it obviously tends to 1 or -1.

Name: Anonymous 2008-08-15 1:33

Actually I believe the answer is 1.154

Name: Anonymous 2008-08-15 5:02

since top and bottom both approach inf cant you just use L'Hopital's?

Name: Anonymous 2008-08-15 8:46

how is the hospital going to help?

Name: 4tran 2008-08-16 4:02

>>11
Yes, you can.

>>12
Troll.

Name: Anonymous 2008-08-18 1:09

>>13
Namefag

Name: Anonymous 2008-08-18 13:41

>>12
troll or not that made me laugh

Newer Posts
Don't change these.
Name: Email:
Entire Thread Thread List