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#1 Re: Help Me ! » Precalculus: Quadratic Functions and Models » 2006-09-22 11:11:14

Wow, this was of great help to me. It was very nice of you to give a method that precalculus students would understand. Thanks a bunch!

#2 Help Me ! » Precalculus: Quadratic Functions and Models » 2006-09-21 14:57:08

Replies: 4

I have little to no idea how to do this problem...

Word Problem wrote:

A rectangle has one vertex on the line y = 10 - x. x > 0, another at the origin, one on the positive x-axis, and one on the positive y-axis. Find the largest area A that can be enclosed by the rectangle.

Any help would be very much appreciated!

#3 Re: Help Me ! » Word Problems (Precalculus) » 2006-09-11 10:57:20

Thanks a bunch!
At first, I was just really confused...I mean, I didn't quite understand what the problem was asking for...But thanks to you, it's all so clear now; I can't believe I couldn't figure it out!

Thanks again.

#4 Help Me ! » Word Problems (Precalculus) » 2006-09-10 18:20:32

Replies: 2

Well, I'm having trouble with this problem mostly because I'm not quite sure what it's asking for...Because of that, I am unable to do part a), which asks for a function.

Word Problem wrote:

Functions and Their Graphs

An open box with a square base is required to have a volume of 10 cubic feet.

a) Express the amount A of material used to make such a box as a function of the length x of a side of the square base.

b) How much material is required for a base 1 foot by 1 foot?

c) How much material is required for a base 2 feet by 2 feet?

d) Graph A = A(x). For what value of x is A smallest?

Any help would be very much appreciated. Hope to hear from you guys soon!

#5 Help Me ! » Optimization Problems (Calculus AB) » 2005-11-30 19:36:38

Replies: 5

I was absent for several days on the account of me being sick...And so, I have no other resource but the MathIsFun forums in order to receive help for my homework during this late night... (I can only hope someone is online and able to help right at this moment...)

I would kindly appreciate anyone who is willing to assist me by informing me on how to work out this problem...My mind has pulled a complete blank...I've tried things that we've went over in the past, but to no avail...It seems that this is new material...material of which I have missed due to my absences.
In any is the problem:

A company estimates that the cost (in dollars) of producing x units of a certain product is given by C= 800 + 0.04x + 0.0002x². Find the production level that minimizes the average cost per unit.

Again...I have very little clue on how to do this, so any form of help would be very much appreciated.

Thanks in advance.

#6 Help Me ! » Depth in Calculus » 2005-10-14 14:23:44

Replies: 8

A conical tank (with vertext down) is 10 ft across the top and 12 feet deep. If water is flowing into the tank at a rate of 10ft³/min, Find the rate of change of the depth of the water when the water is 8ft deep.

...I'm pretty sure it's asking for dh/dt (or dD/dt, OR Rate of change of the depth.) Problem is...I can't seem to figure out what formula to use...
Any help would be very much appreciated. Thanks in advance!

#7 Re: Help Me ! » Trig in Physics? » 2005-10-06 10:22:16

Thanks so much Derek. I pretty much understood the rest of it, but I missed the part where M cancels out...In fact, no one in my class got the question right.
In any case, this really helps me and I'll keep it in mind for future reference. Thanks again.

#8 Help Me ! » Trig in Physics? » 2005-10-05 12:55:06

Replies: 2

A crate starts from rest and slides 8.35 m down a ramp. When it reaches the bottom it is traveling at a speed of 5.25 m/s. If the ramp makes an angle of 20.0° with the horizontal, what is the coefficient of friction between the crate and the ramp?

Does anyone know how to solve this? I've tried all that I can to my knowledge, but I've yet to come up with a solution. Of course, I'm guessing that's natural because we're barely starting this unit, but I still want to know how this problem can be solved. If possible, please help me with what steps I should follow...I believe I know the equations, but where to apply them is what I don't. Thanks in advance.

#9 Re: Help Me ! » Trig: Pythagorean Identites » 2005-10-03 12:46:55

Yeah, I went over it more indepth today with my teacher 'cause I told her I didn't understand much. She was really nice about it and I believe that I am actually starting to remember several of these identities. Thanks for your guys' help as well though, wouldn't have been able to do my homework that night without it.

#10 Help Me ! » Trig: Pythagorean Identites » 2005-09-29 12:37:44

Replies: 3

Can someone tell me the pythagorean identites that are used for trig?

So far, I know that sin² x + cos² x = 1 and cos² x = 1 - sin² x. I skipped several math classes and headed straight for AP Calculus...Everything else is pretty easy, but I can't seem to get the trig down.
A list of all the pythagorean identites would be very much appreciated.
Thanks in advance.

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