Mathematics
12 Online
OpenStudy (anonymous):
Find the limit as x->-1 of (x^2+1)/(x+1). i've forgotten how to figure out problems when denominator = 0
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OpenStudy (akshay_budhkar):
l' hospital rule,
differentiate the numerator n denominator
OpenStudy (akshay_budhkar):
do that till u get a determinate form
OpenStudy (anonymous):
never learned a hospital rule
OpenStudy (anonymous):
can someone do steps pls?
OpenStudy (akshay_budhkar):
ok you differentiate the numerator and the denominator and then substitute the value of x
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myininaya (myininaya):
no you can't use l'hospital here
OpenStudy (akshay_budhkar):
why :O
myininaya (myininaya):
\[(-1)^2+1=1+1=2 \neq 0\]
OpenStudy (akshay_budhkar):
lol sorry :P mathematical error :P
OpenStudy (anonymous):
can someone please just do a quick list of steps
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OpenStudy (anonymous):
so i can figure out others like it
myininaya (myininaya):
the function is undefined at x=-1
this is not a hole so the limit does not exist
OpenStudy (anonymous):
yes it does, the answer is -2
myininaya (myininaya):
no the limit does not exist
myininaya (myininaya):
you typed your wrong if the answer is -2
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OpenStudy (anonymous):
i did
OpenStudy (anonymous):
my fault, fml
OpenStudy (akshay_budhkar):
lol
OpenStudy (anonymous):
x^2-1****
myininaya (myininaya):
\[\lim_{x \rightarrow -1}\frac{x^2-1}{x+1}=\lim_{x \rightarrow -1}\frac{(x-1)(x+1)}{x+1}\]
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OpenStudy (akshay_budhkar):
lol myininaya u r too quick :P
OpenStudy (anonymous):
damn
myininaya (myininaya):
now you also use l'hospital if you wanted to since we do have 0/0 here
myininaya (myininaya):
but i mean you don't have to
you can just use some algebra
myininaya (myininaya):
like i did above (x+1)/(x+1)=1
so you are left with (x-1) just plug in -1
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OpenStudy (anonymous):
yeah
OpenStudy (anonymous):
ty
OpenStudy (anonymous):
Limit is +Infinity from the right and -Infinity from the left. Plot attached.
OpenStudy (akshay_budhkar):
yeah limit at that point doesn't exist as left hand limit is not equal to right hand limit. But he made an error with the question its x^2-1 not x^+1