***Official AP Calculus BC Thread 2014-2015***

I was told a critical point was whenever the derivative was 0 or undefined, I actually tried k=-5, but if you plug it into the original function you get undefined or indeterminate, I forget which, I don’t think you can have a critical point at a value of x where f(x) is not continuous. I had 30 plus the integral from 0 to w of R(t)-D(t) dt = 50.

@sjwon3789 I think the main issue is that they explicitly said the formulas they gave are valid UNTIL it overflows. So greater than wouldn’t make sense, because technically you have no idea what happens after it overflows. You know the time at which it will overflow, but not necessarily that it will stay overflowed after that.

So no general term or something? Or did they ask for a general term?

That related rates with sinx was bs

@Dorfdude8 They only asked for the first four terms, but the general term was pretty obvious.
@sjwon3789 Maybe, by some wierd chance, you’re the only one I know out of like 20 people I’ve talked to who got it right. But, I’m relatively sure it asked for the time w when it begins to overflow.

@synack The difference between inequality and equal sign is basically the interpretation of the problem. Inequality would mean afterward, whereas equal would mean inclusive. I thought the point would not be overflowing, so it wouldn’t count. So after you solve for w, you would write “after time w” technically, rather than at time w.

@sjwon3789 Also, I was unsure at the beginning, so I made sure to read the word “equation” like 3 times to make sure :P.

So I put in the first four terms, but on the bottom I put something like 3/1+x for whatever reason XD I assume AP will grade me for the wrong answer?

Yea I think its inequality because at the exact moment you can perfectly fill it up

@Frigidcold @chocomilk for the MC about when the slope was dependent on only y i put I only. Because for II and III the slope changed when x changed. Only l was a straight line because the y didn’t change so the slope never changed… right?

lol i feel like crying. i probably failed.

the area is just the area under the curve from 0 to k, if you differentiate both terms wrt t and you’d have sin k dk/dt, right?

@sjwon3789 Since you don’t have any information about what happens after time w, I don’t think you can say that it overflows “after time w”. For all you know, it could overflow briefly at time w and then drop again.

@Frigidcold Lol I saw that too but it didn’t make sense because I thought it had to be afterward, since it’s not overflowing exactly at time w. I ignored it and I forgot to come back lol

I’m guessing I got little to no points on calculator portion.

@jetynz I don’t know how you came to that conclusion for II. I would argue that II changed slope as y changed. It doesn’t necessarily have to be a straight line. Because as y changes, the slope changes.

How about that MVT multiple choice on non calc part?

@synack Why would it overflow at time w when it’s exactly at 50 at time w? The moment when it starts overflowing is after w, not necessarily continuously. That’s not what the problem was asking for. It simply asked when it starts to, but it doesn’t at time w.

@Dorfdude8 Yeah that second part would be incorrect. Pretty sure that you would have to use a/1-r. Just plug in values.

@Frigidcold Does I count because the slope doesn’t change at all?