Official "Help me with my homework" thread

[elcuebee]

Prove the closed ball is closed.

FILL WITH WATER SEE IF IT LEAKS LOLZ

get an object that is the exact same size and weight and thickness (in terms of the sphere's shell so to speak) as your ball that you have to test if it's closed, and that is confirmed to be sealed/closed

then weigh it

put it in water and submerge it with a tool, and time how long it takes to come up to the surface and check it's weight every time, do this about 10-15 times to accomodate for any bizarre results that would screw up the data

then figure out the average of those results, what the weight was before it was put in water and after each test etc. i'm sure you get it

then get your supposedly closed ball, and repeat test as above

if test results are strikingly similar, then the second ball that you just ran through the tests is also closed, as it would have to be to not take in water/get it's weight changed through submerging it and thus maintain the same results

[TaQa]

loller

Sorry I needs it in math words.

Edit:

Maybe I wasn't clear on what the question is.

A ball is closed if it satisfies this condition:



Where M is a generic metric space, p is a point in that space, and r is the radius of the ball.

Prove that this is a closed set.

[chocobojoe]

what the hell are you majoring in?

[Riot]

[BigBadOrc]

what the hell are you majoring in?

yes that's what you learn in math after ur done with calculus. he's gonna tetch lil kiddiez about metric spaces

dude i wanna be a math teacher !


TETCH ME WIGGLES MR. WIKIPEDIA!

In a metric space, a set is closed if every limit point of the set is a point in the set... SO BASICALLY...

if you are "outside" a closed set and you "wiggle" a little bit, you will stay outside the set

[blackcat]

what the hell are you majoring in?

He's majoring in math ed.