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Mathematics 19 Online
OpenStudy (bahrom7893):

lim as x approaches 4 of (2x^2+32)

OpenStudy (anonymous):

replace x by 4

OpenStudy (bahrom7893):

lol satellite this wasn't for you, come on..

OpenStudy (bahrom7893):

lgba go ahead and give me the answer.. then i'll show you something else..

OpenStudy (lgbasallote):

maybe you meant lim x-> 4 of (2x^2 - 32)?

OpenStudy (bahrom7893):

no i meant what i posted, just give me the answer..

OpenStudy (lgbasallote):

64

OpenStudy (bahrom7893):

All right, that's what i was getting at. Now prove that the lim as x->4 (x^2+32) = 64 lol

OpenStudy (bahrom7893):

*sorry meant 2x^2+32

OpenStudy (bahrom7893):

i already proved this, just wanna see your approach

OpenStudy (lgbasallote):

prove that 2x^2 + 32 = 64?

OpenStudy (bahrom7893):

lol satellite's answer was kinda embarrassing for me... :/ a junior in college and a math major and can't solve limits

OpenStudy (bahrom7893):

No, prove that the lim as x->4 of 2x^2 +32 = 64

OpenStudy (bahrom7893):

U might not be familiar with the proof if u didn't take advanced calc.. i actually liked how the proof works

OpenStudy (rogue):

With epsilons and deltas? The formal way of doing limits is so boring.

OpenStudy (anonymous):

my proof is that polynomials are continuous functions, cue ee dee

OpenStudy (bahrom7893):

by the way.. hint: delta = min {1, epsilon/18}

OpenStudy (bahrom7893):

yea lol rogue.. haha satellite

OpenStudy (lgbasallote):

my proof is the definition of limits

OpenStudy (bahrom7893):

that's for derivatives lol

OpenStudy (bahrom7893):

meh.. i guess we can stop here then. haha just factor |2x^2+32-64|

OpenStudy (bahrom7893):

Then u'll end up with: 2|x-4||x+4|<epsilon |x-4||x+4|<epsilon /2

OpenStudy (bahrom7893):

Suppose |x-4| < 1 (let delta = 1)

OpenStudy (lgbasallote):

too much math terms @_@ error error error

OpenStudy (bahrom7893):

that means: -1 < x-4 < 1 adding 8 to everything gives: 7 < x+4 < 9 So you get: |x-4||x+4|<|x-4|*9 (since |x+4|<9)

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