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Mathematics 9 Online
OpenStudy (anonymous):

find the limit as x approaches 2 from the left of x/x-2

OpenStudy (agent47):

it's negative infinity, if I'm not mistaken

OpenStudy (anonymous):

i know the answer is negative infinity but why? Do i have to plug 2 into the x/x-2?

OpenStudy (agent47):

ok this is why..

OpenStudy (anonymous):

it was a homework problem and she gives us the anwers but i dont get how to get negaitve infinity

OpenStudy (agent47):

as x approaches 2 from the left, or: x=1.99999, x=1.99999999999, x=1.99999999999999999, x=1.99999999999999....999999, the bottom of that fraction approaches "negative zero"

OpenStudy (agent47):

or the denominator will get very close to: -0.0000000001, -0.0000000000001, -0.000000..........00000001

OpenStudy (agent47):

So as the bottom gets small, the fraction blows up.... but since the bottom is negative and the top is positive, the whole thing approaches negative infinity.

OpenStudy (anonymous):

ohh that makes sense now

OpenStudy (agent47):

So do you like my monkey?

OpenStudy (anonymous):

so its negative infinity because its approaching 2 from the left?

OpenStudy (agent47):

yea, if it were approaching from the right, it would have been positive infinity.

OpenStudy (anonymous):

gotcha. thanks!

OpenStudy (agent47):

because you'd be getting: 2.0000000000000001 2.00000000000000000000000001 so the bottom wld be: 0.0000000001 0.0000000000000000000001 so the whole thing wld approach positive infinity.

OpenStudy (agent47):

By the way, actual limit of x/(x-2) as x approaches 2 doesn't exist. For it to exist the right and left hand limits must equal each other, but here one is negative and one is positive infinity, so the limit does not exist. If both were approaching -inf, the answer wld be -inf, if both were approaching positive inf, the answer wld be positive inf.

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