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Topia
Registered User regular

Okay this is very very easy stuff so you smart folk shouldn't have a problem. I am studying for a calc test (yes studying so I'm not cheating) and have problems with just this one question so far.

Indicate limit:

lim .....__| x - a |__

x->a- (x^2) - (a^2)

Now I know the answer is -(1/2a)

Help! This shouldn't be so hard, but I am having problems right now.

Indicate limit:

lim .....

x->a- (x^2) - (a^2)

Now I know the answer is -(1/2a)

Help! This shouldn't be so hard, but I am having problems right now.

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## Posts

EDIT: it's been a while since calc, but I think you have to invoke L'Hopital's rule.

EriosonEdit: there is another question exactly the same that is a+, so a from the right, or positive side, too.

TopiaonL'hopital's Rule

GameHatonphysi_marconSwitch Friend Code: 3102-5341-0358

Nintendo Network ID: PhysiMarc

I guess this is my answer. I tried but must have made a mistake somewhere along the way. L'HÃ´pital's rule hasn't come up yet.

TopiaonJust remember that if you are approaching a from the left, X<=a. So |X-a| will always be equal to a-x.

approaching a from the right, then X>=a. And |x-a| = x-a.

otherwise factoring the bottom won't help you.

GameHatonilmmadonTopiaonIt is probably the greatest thing.

EriosonYea, we're past differentiation and integration, but our teacher wants us to do certain questions certain ways... even if there is an easier way to do it. I find the derivatives, chain rule, all that way easier than basic algebra, strangely, but I am not allowed to use differentiation to find these answers on the test.

He gives us an idea of whats on the test (6 limit questions, 4 differentiations, ect) and tells us that we have to do this for these questions, all that jazz. It's irritating.

Edit: L'Hôpital's rule seems pretty easy, we probably went over it, but the prof probably didn't call it that.

Topiaon