Author Topic: Matho-Man Ask me any math question!  (Read 4095 times)

Uhmmm.........

Forget it.  People keep on posting... :(((

I have a TI-89, can take derivatives and integrals n such.
TI-89 is a waste of money quite frankly.

TI-89 is a waste of money quite frankly.
Derivatives are easy ;o




Another question about absolute maxes and mins.

f(x)= x+sin(x)

On the interval [0,π] find the absolute max and min.

I must have been screwing something up as I had a hard time getting an answer.
« Last Edit: November 13, 2008, 08:55:54 PM by Otis Da HousKat »


Derivatives are easy ;o




Another question about absolute maxes and mins.

f(x)= x+sin(x)

On the interval [0,π] find the absolute max and min.

I must have been screwing something up as I had a hard time getting an answer.

Well, first take your derivative. Because derivative gives us the slope at any point. and because maxs and mins have slopes of 0. we would set our derivative to 0.

first: f'(x)=cos(x)+1
so we set that equal to 0

0 = cos(x)+1
and we solve for x.
-1 = cos(x)
arccos(-1) = x
x = pi or 3.14159

so that is our x value at an absolute max or min. you find y values to the left and right of that x value to find out if it is a max or min.



What is the real positive number such that the number and it's inverse is as small as possible?

That was a question on my math test yesterday. No clue what to do so I bullstuff my way to some (wrong) answer.


Calculus 1 in college by the way.


Infinity. that is what I presume

TI-89 is a waste of money quite frankly.

Not really mine costed $50. cheaper than what you paid for your TI-84

Well, first take your derivative. Because derivative gives us the slope at any point. and because maxs and mins have slopes of 0. we would set our derivative to 0.

first: f'(x)=cos(x)+1
so we set that equal to 0

0 = cos(x)+1
and we solve for x.
-1 = cos(x)
arccos(-1) = x
x = pi or 3.14159

so that is our x value at an absolute max or min. you find y values to the left and right of that x value to find out if it is a max or min.



Infinity. that is what I presume

The work you showed is as far as I got. I was under the impression that I should plug the critical points and end points( 0 and pi) back into f(x) to check their values. That would tell me their y value. The end points because it's a closed interval and the critical point because that's where x would be lowest or highest before turning around.

f(0)=0+sin(0)=0
f(pi)=pi+sin(pi)=pi

I was unsure of what to do with those though as it looked weird to me.

For the second one, work would be nice ;o

I played around with some infinity and negative infinity bullstuff. I heard the answer was 1 or something though, not sure yet.

What is the real positive number such that the number and it's inverse is as small as possible?
Keep in mind I don't actually know a thing about math compared to you

Wouldn't that be any number? And isn't infinity not a real number?

What is 2+2 in base 4?

What is 2+2 in base 4?
Why do people keep asking stupid stuff like 1.23434534534+1.424345434= and what is pi?