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#26 Re: Help Me ! » how do i integrate this? » 2011-07-23 23:56:07

oh wait i missed out the definite integrals, its between pi and 0

the answers says 2pi/3

#28 Help Me ! » probability question binormal distribution » 2011-07-23 22:42:35

nevinsmith
Replies: 18

A small restaurant seats 20 diners and is full every night. There are only 12 steaks available and 40% of diner tables will request a steak, indepedent of each other.
one table can only order one steak.

If a customer orders a steak, what is the probability that he/she will recieve it?

Any tips? I can't seem to get the answer which is actually 0.996315 to 6sf

#29 Introductions » Hi everyone » 2011-04-14 00:38:36

nevinsmith
Replies: 2

hi people!

Im nevin and im from new zealand!
im 17 and desperately trying to understand calculus in my high school at the moment

my teacher is quite retarded in that he only has a degree in psychology and
doesnt know much beyond differentiation

this is why you guys will be my best teachers!!!

thanks for helping me

#30 Help Me ! » statistics summation question » 2011-04-14 00:33:29

nevinsmith
Replies: 2

hi guys me again!

Q- Jack and Morgan are gambling, on a roulette wheel there are 10 blacks and 30 reds, they both take turns at spinning the wheel, the first person to land their dice on black wins.
If jack goes first, what is his probability of winning?

so i figured out this is a summation question to infinity

b=1/4    r=3/4

the probability would be
b+brr+brrrr+brrrrr.....

so b+ b(sum of n=0 n=inf)(r^2)^n
where r<1

now how do i solve this?

sorry i don't know how to write the summation notation on here!
now how do i solve this?

#31 Re: Help Me ! » Help with binomial expansion! » 2011-04-14 00:22:05

yea i would think there is a print error

the origional problem was probably what gAr said it was

the book is pretty darn useless at explaining stuff
thanks for the help guys!

#32 Re: Help Me ! » Help with binomial expansion! » 2011-04-12 20:11:49

hi bob bundy, thanks for helping

so i expand 1/3(1/3x2+1)^-1

i still get the terms in fractions with convergence of every value of x

1/3-(x^2)/9+(x^4)/27-(x^6)/81.....           

can you please explain how the answer is different?

which is              3-9x^2+27x^4-81x^6....                        true for -sqrt3>x>sqrt3

how did the terms not have fractions?

thanks for your reply

#33 Help Me ! » Help with binomial expansion! » 2011-04-12 19:51:41

nevinsmith
Replies: 14

so the question is expand 1 / (x^2+3)

so i take 1st term as x^2, 2nd term as 3 and power as -1

using binomial series i got-

1/3-(x^2)/9+(x^4)/27-(x^6)/81.....            true for all values of x???

but the answer says-

3-9x^2+27x^4-81x^6....                        true for -sqrt3>x>sqrt3

??? why does that happen?
is it to do with requirements of convergence or am i just wrong?

so how do i calculate the valid values of x for convergence?

#34 Re: Help Me ! » product rule problem » 2011-02-12 14:42:04

thanks for your help bobby now i understand!

#35 Help Me ! » product rule problem » 2011-02-11 14:22:02

nevinsmith
Replies: 3

hi guys, so i understand that the product rule can be applied

when finding dy/dx for-       

y=f(x)g(x)

then dy/dx=f'(x)g(x)+g'(x)f(x)

but what happens if you are trying to find dy/dx for

y=f(x)f(u)

where u is a function of x as well?

for example y=f(x) (ln g(x))

do you use chain rule or is it just the same thing?

#36 Help Me ! » Differentiation problem » 2011-02-08 21:42:18

nevinsmith
Replies: 1

hi guys, im stuck on a question

find dy/dx   for equation

y=(8x)^(x-2)

i think im missing a rule to differentiate y=f(x)^g(x)
please help
thnx

#37 Re: Help Me ! » probability and circles!!!! » 2010-05-25 18:47:28

mathsyperson- thnx for the solution! ya your right it means intersect only inside the circle. i kinda thought it was something like that but didn't think it was equal in probability haha. thnx everyone

#38 Help Me ! » probability and circles!!!! » 2010-05-21 00:08:56

nevinsmith
Replies: 11

a circle has it's circumference evenly distributed with 2010 dots, 4 dots chosen at random are a,b,c,d

find the probability of line segments a-b  intersecting with c-d!

i don't know how to do it please help me!

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