calc help pleeeeeeeeeeeeease

[Wezil]

So is this thread open for spam now?

[Victor Galis]

The trick is to take 1 million practice exams then have your grade depend on the percentage you got on those practice exams uncurved. So when the real thing comes around, even the guy that flunked the course gets a 5. At least that seemed to work for our teacher.

I started my multivariable calc course while still 16, sadly I don't remember much of it What's really sad, is that I really should or I might flunk my macroeconomics midterm next week.

[Wiglaf]

Your teacher is moving too slowly for BC, please tell him to speed up.

Also I recommend the movie Stand and Deliver. It is the riveting story of a bunch of Mexicans doing well on an AP calculus test and being accused of cheating. These kids are so stupid, it makes you think you can do it if they could. I am pretty sure they cheated, not being racist but they were so dumb.

[Wezil]

Your avatar is disturbing.

[b etor]

ok so for B. i put A(x) = sqrt(64-x²) * x which i'm assuming is correct.
so for C. can i just put that x is less than 8 and greater than 0? or is there a formula i need to use? cuz it looks like it's around four but i can't prove that.

[Kuciwalker]

C is correct, though it should be "less than or EQUAL TO" and "greater than or EQUAL TO"

[b etor]

but how can it equal zero? then it'd just be lines and no shape?

[snoopy369]

Originally posted by b etor
so for C. can i just put that x is less than 8 and greater than 0? or is there a formula i need to use? cuz it looks like it's around four but i can't prove that.

Given your formula for A(x), what is the maximum X?

A(x) = x * sqrt(64-x^2)

x > 0 is minimum of course

For what value of X is this function no longer a legal function? That is your domain

Spoiler:

(0..8] is the domain, if I remember the notation properly. That's based on a 0 area being illegal; i'm not sure if it is or not, if it is not then [0..8] is the domain.

[snoopy369]

Originally posted by b etor
but how can it equal zero? then it'd just be lines and no shape?

If Kuci's right, which I have no reason to believe he's wrong, the issue is that this isn't really geometry; it's a theoretical function problem. If this were engineering then clearly the range would be different (as 0 would be illegal); but it's not Get used to theoretical math allowing anything that is allowed under the rules of math, not just the rules of reality

[b etor]

ohhh no not more ()'s and []'s!!

[Kidlicious]

Originally posted by Wiglaf
Your teacher is moving too slowly for BC, please tell him to speed up.

I'm sure she will get beat up by the other students for that.

[Kuciwalker]

Originally posted by b etor
but how can it equal zero? then it'd just be lines and no shape?

Yep, but the functions are all still well-defined there and have a meaningful geometric interpretation (triangle of area zero).

[Jonny]

Mathematically, 0 and 8 are in the domain. But since they don't make sense in the given problem, I wouldn't include them (since in those cases, there isn't a rectangle anymore, just a line).

[snoopy369]

Like I said I'm not sure I recall the correct meaning of ( [ ] ) in domains... I think [] means GE/LE and ( ) means G/L (exclusive) but it's been twelve years...

FWIW I took calculus at 15 also, and loved it, but then hated pretty much all math beyond 3rd semester calculus... torsion and such just gave me nightmares

[Kuciwalker]

They do make sense.