Posted by **susan** on Wednesday, July 20, 2011 at 9:30am.

i really dont understand why this 1-lim 3/(y+4) [the lim is x->infinity] the ans is 0 while this 2-lim (7-6x^5)/(x+3) [x->+infinity ] is - infinity.

can anyone explain why the 1 is zero & the 2 is infinity.

- math -
**Reiny**, Wednesday, July 20, 2011 at 1:20pm
Try to get a "feel" for numbers.

look at 3/(y+4)

As the y+4 gets larger and larger, and since the top stays constant at 3, the quotient gets smaller and smaller.

e.g. let y = 1 000 000, (not even close to infinity)

the quotient is 3/(1000000 +4) = 0.000003

pretty close to zero, but we have a long way to go in making y ---> infinity

for the (7 - 6x^5)/(x+3) , x--->+infinity

pick a "large value of x" , say x = 1000

so you would get (7 - 6000 000 000 000 000)/1003

would you not agree that this is a huge negative number ? And our x is not even remotely "large".

You might even want to experiment with your calculator.

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