calc help pleeeeeeeeeeeeease

[b etor]

ok so i've been taking this online AP calc course because i completed all of the other available ones but i'm having a really hard time with it.
i don't like math anymore. at all.
and i have an assignment that's due in like 5 hours which i have almost completed, but i have no idea how to even start one. i went through all my notes and the lessons, but i can't find anything that says how to do it.
i'm probably just being stupid but i've been trying to figure this out for a while and it is REALLY frustrating me.
my whole family is at the movies right now. i stayed home to tackle this.
will you smart people pleeeease help me? my parents have no idea what's going on, and my older sister is in pre-calc so she doesn't understand it either.
and it's only functions!


that's a screen shot of it that i just condensed.

i'm not asking for answers, i just want to know how to start it.

[Wezil]

The usual response - Someone asks for "help" and then 20 posters post the answer. Is this what you want (the anser rather than the help getting to the answer)?

edit - nm, I see you still want to tackle it.

[b etor]

no, i really need to know how to do the work for this ****.

[Wezil]

I'd help you but I haven't done calc in over 20 years. The knowledge has seeped out.

[b etor]

uh huhhh.

[Wezil]

It will happen to you too. You'll see.

[b etor]

A. y = sqrt(8²-x²)?

[Kuciwalker]

A. You have a right triangle with sides length x and y and hypotenuse length 8. Apply the Pythagorean theorem, then some algebra and you have y in terms of x.

B. A(x) = x * y. Since you already know y in terms of x, substitute that and you have A(x) = x * f(x).

C. Just figure out what values of x are possible given the geometry. Clearly x can't be less than zero, and the upper bound is equally obvious.

D. Easy once you have A(x).

E. ... it's kinda obvious I can't help you here.

[Solver]

Calculus at 16? Then again, it's not really calc...

WTF is A(x)? Never seen similar notation. Anyway,

1. You should be able to do that. 64 = y^2 + x^2. From there, you should be able to express y as a function of x.

2. If A(x) is just what they want to name the function, write how to compute the area of the rectangle.

3. The domain shouldn't be hard to determine. For a rectangle to exist, it needs to two valid sides, of course.

4, 5. You should be able to graph the function yourself. Some description will probably come to you when you have the pic.

[Kuciwalker]

Originally posted by b etor
A. y = sqrt(8²-x²)?

Yep.

[Kuciwalker]

Originally posted by Solver
Calculus at 16?

I started taking real calc when I was 14

[Solver]

Originally posted by Kuciwalker

Originally posted by Solver
Calculus at 16?

I started taking real calc when I was 14

"Real calc" as in starting with derivatives?

[Kuciwalker]

No, as in integral calculus and basic differential equations (didn't take a full-fledged diffeq course until senior year). We did derivatives in precalc (freshman year of HS). Maybe we spent a week going over them again at the beginning, I don't recall.

[Solver]

Gee. And people don't believe me when I say that it sucks that our highschools don't have any calculus - not even the concept of a derivative.

[Kuciwalker]

I went to a rather special highschool, and was in the top 5-10% there. That said, all the regular highschools around me had at least up through the real calc course I mentioned (though not that many take it).