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Calculus1 9 Online
OpenStudy (zappy620):

Help with limits please

OpenStudy (zappy620):

\[\lim_{x \rightarrow 0}\frac{ (2+x)^{3}-8 }{ x }\]

OpenStudy (zappy620):

The answer in the book is 12 and I can't seem to figure out how they got it.

satellite73 (satellite73):

multiply

OpenStudy (agent0smith):

Did you try simplifying the numerator...

OpenStudy (s4sensitiveandshy):

are you familiar with L'Hospital Rule ?

OpenStudy (agent0smith):

^You could but no need for it. Simplify and you'll see why.

satellite73 (satellite73):

this comes way way before l'hopital

OpenStudy (zappy620):

actually i just figured out i was just multiplying the factors wrong smh

satellite73 (satellite73):

\[(2+x)^3=?\]

satellite73 (satellite73):

yeah it is always algebra that messes up

OpenStudy (zappy620):

\[x^{3}+6x ^{2}+12x+8\]

OpenStudy (zappy620):

is there a trick on multiplying that out faster?

OpenStudy (zappy620):

well just to finish off the problem I guess, after factoring out the x's and getting rid of the 8s, im left with

OpenStudy (zappy620):

\[x ^{2}+6x+12\]

OpenStudy (zappy620):

\[(0)^{2}+6(0)+12=12\]

OpenStudy (s4sensitiveandshy):

\[(a+b)^3 =a^3+b^3+3a^2b+3ab^2\] but i guess it's easy to draw a box and distribute (a+B)(a+b) and then quadratic by (a+b) helps me to stay way from mistakes

OpenStudy (zappy620):

oh wow i forgot about that forumla :o tyvm

OpenStudy (agent0smith):

"Simplify and you'll see why." That rhymed.

OpenStudy (zappy620):

Haha it does :P

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