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Re: Nairaland Mathematics Clinic by Laplacian(m): 9:40pm On Oct 30, 2013
Mbahchiboy: bross biko just finish d no 1 to fulfil all righteousness.....
to d no two how did u get dat answer?EXPLAIN!
wat is there 2 finish in no.1..biko....
Just dat he made a HARMLESS mistake in d genral solution...
y=(Ax+B)e^-x
...for number 2, d numer of digits in any given number n, say, is given by Logn (approx.)
number of digits in
2004^2004=2004*Log2004 (approx.)
Re: Nairaland Mathematics Clinic by Mbahchiboy(m): 9:43pm On Oct 30, 2013
Cashio: i wondered really if jackpot is truly a girl/lady cos i have never seen any female with such IQ....thumbs up sis/bro.
LOL..........
Re: Nairaland Mathematics Clinic by Mbahchiboy(m): 9:55pm On Oct 30, 2013
Laplacian:
wat is there 2 finish in no.1..biko....
Just dat he made a HARMLESS mistake in d genral solution...
y=(Ax+B)e^-x
...for number 2, d numer of digits in any given number n, say, is given by Logn (approx.)
number of digits in
2004^2004=2004*Log2004 (approx.)
no qualms 4 d no 1 sir.....
4 d no 2 i got wat u said but i wud like to know how e got those digits,i dont mean d number of digits but d digits itself
Re: Nairaland Mathematics Clinic by Nobody: 10:48pm On Oct 30, 2013
I have some unsolved math problems ....but if i post them now ... U guys will start saying that i'm testing ur ability or this and that...... No problem sha ....i see i'm not welcome here ....4 reasons not clear 2 me ....i'l kindly unfollow ur thread now .....enjoy
Re: Nairaland Mathematics Clinic by Mbahchiboy(m): 10:53pm On Oct 30, 2013
Swagalord18: I have some unsolved math problems ....but if i post them now ... U guys will start saying that i'm testing ur ability or this and that...... No problem sha ....i see i'm not welcome here ....4 reasons not clear 2 me ....i'l kindly unfollow ur thread now .....enjoy
taking tins too personal.
*smh*
Re: Nairaland Mathematics Clinic by jackpot(f): 10:58pm On Oct 30, 2013
Mbahchiboy: no qualms 4 d no 1 sir.....
4 d no 2 i got wat u said but i wud like to know how e got those digits,i dont mean d number of digits but d digits itself
to get the digits itself, take antilog to base 10 of the mantissa of (2004*Log102004).

1 plus the integral part of (2004*Log102004) gives you the number of digits of 2004^2004.


Elementary reasoning.
Re: Nairaland Mathematics Clinic by statusnet(m): 10:59pm On Oct 30, 2013
smurfy: Four married couples bought eight seats in a row for a concert. In how many ways can they be seated if
(a) each couple is to sit together
(b) each couple, except a particular newly-wed couple, is not to sit together
(c) a particular couple decided to head home after having a minor argument?

a) If each couple is to sit together then it will be 4! and each individual couple can sit in 2 ways
Then 4! * 2(4) = 192 ways

b) since three of the couples can sit in any arrangement then they're treated as 6 ppl and the remaining couple can sit in two

Therefore, 6! * 2 = 1440

c) we weren't told a particular arrangement and with the exception of a couple

6!= 720

cool cool
Re: Nairaland Mathematics Clinic by jackpot(f): 11:11pm On Oct 30, 2013
Swagalord18: I have some unsolved math problems ....but if i post them now ... U guys will start saying that i'm testing ur ability or this and that...... No problem sha ....i see i'm not welcome here ....4 reasons not clear 2 me ....i'l kindly unfollow ur thread now .....enjoy
Hi Mr Swagalord

pls do post them, but make it open for anybody to solve and eat the sumptuous meal. wink

You know, I have been eating your sumptuous meals and I'm now obese. Hope you understand? wink wink
Re: Nairaland Mathematics Clinic by Mbahchiboy(m): 11:59pm On Oct 30, 2013
jackpot: take Log10 of 2004 and multiply by 2004.

1 plus the integral part of (2004*Log102004) gives you the number of decimal places of 2004^2004.


Elementary reasoning.
hmm...........
Re: Nairaland Mathematics Clinic by Mbahchiboy(m): 12:00am On Oct 31, 2013
Mbahchiboy: TO MY GENERALS:MAKE UNA DO DIS 1 4 ME::
if S=a(r^n-1)/r-1....
make r d subject of d formular
Re: Nairaland Mathematics Clinic by jackpot(f): 1:36am On Oct 31, 2013
@Mbahchiboy, find below what you sought for (i.e., the few digits of 20042004)
jackpot: to get the digits itself, take antilog to base 10 of the mantissa of (2004*Log102004).

should I throw more light?
Re: Nairaland Mathematics Clinic by jackpot(f): 1:41am On Oct 31, 2013
Mbahchiboy: TO MY GENERALS:MAKE UNA DO DIS
1 4 ME::
if S=a(r^n-1)/r-1....
make r d subject of d formular
for n>=6, subject of the formula may not be possible.
Re: Nairaland Mathematics Clinic by Nobody: 9:13am On Oct 31, 2013
Okay ..thanks y'all ....was expecting a "good riddance" kind of reaction .
.
.
Here'z breakfast .....dont let it get cold,,,
.
.
Show that a-b/a_|b - b_|a = 1/_|a + 1/_|b
.
* a_|b means (a root b)
Re: Nairaland Mathematics Clinic by AlphaMaximus(m): 9:56am On Oct 31, 2013
Re: Nairaland Mathematics Clinic by Mbahchiboy(m): 10:09am On Oct 31, 2013
Swagalord18: Okay.thanks y'all .was expectin a"good riddance"kind of reaction.
Here'z breakfast .dont let it get cold,,
Show that a-b/a_|b - b_|a = 1/_|a + 1/_|b
*a_|b means (a root b)
let roota=x..dat means a=x^2
let rootb=y..dat means b=y^2.
so ur ques a-b/a(rootb)-b(roota) becomes::
x^2-y^2/(x^2y-y^2x)..
which is (x-y)(x+y)/xy(x-y).
d result is: x+y/xy;
x/xy+y/xy=
1/y+1/x=
1/x+1/y:
recal:x=roota,y=rootb.

1 Like

Re: Nairaland Mathematics Clinic by Mbahchiboy(m): 10:14am On Oct 31, 2013
jackpot: @Mbahchiboy, find below what you sought for (i.e., the few digits of 20042004)

should I throw more light?
i think so....or do u mean d antilog of 6618?
Re: Nairaland Mathematics Clinic by rhydex247(m): 10:22am On Oct 31, 2013
Laplacian:
wat is there 2 finish in no.1..biko....
Just dat he made a HARMLESS mistake in d genral solution...
y=(Ax+B)e^-x
...for number 2, d numer of digits in any given number n, say, is given by Logn (approx.)
number of digits in
2004^2004=2004*Log2004 (approx.)
Hmmmmmmmmmmm. For the no 1 solution.
recall that in the case of REAL AND EQUAL ROOTS: m=m1 (twice).
hence the general soln is y=e^m1x(A+Bx).
comparing to my solution y=Ae^-x+Bxe^-x or y=e^-x(A+Bx). hence my answer still dey kampe.

For the no 2 answer no be magic na ogbanje spiritual calculator I take solve am. lollll
Re: Nairaland Mathematics Clinic by Mbahchiboy(m): 10:27am On Oct 31, 2013
jackpot: @Mbahchiboy, find below what you sought for (i.e., the few digits of 20042004)

should I throw more light?
I GET U NOW MISS..TNX
Re: Nairaland Mathematics Clinic by Mbahchiboy(m): 10:31am On Oct 31, 2013
rhydex 247:
Hmmmmmmmmmmm. For the no 1 solution.
recall that in the case of REAL AND EQUAL ROOTS: m=m1 (twice).
hence the general soln is y=e^m1x(A+Bx).
comparing to my solution y=Ae^-x+Bxe^-x or y=e^-x(A+Bx). hence my answer still dey kampe.

For the no 2 answer no be magic na ogbanje spiritual calculator I take solve am. lollll
haha.....i like see dat calculator..
Re: Nairaland Mathematics Clinic by Nobody: 10:39am On Oct 31, 2013
statusnet:

a) If each couple is to sit together then it will be 4! and each individual couple can sit in 2 ways
Then 4! * 2(4) = 192 ways

b) since three of the couples can sit in any arrangement then they're treated as 6 ppl and the remaining couple can sit in two

Therefore, 6! * 2 = 1440

c) we weren't told a particular arrangement and with the exception of a couple

6!= 720

cool cool

Good try statusnet. You got (c) right.

Here goes...
(a) Each couple as a unit can sit in 2! ways and each of the four two-unit couples can sit in 4! ways. That gives 48.

(b) 8! - (2! * 7!). Total number of ways of sitting without restriction is 8! (=40320). Total number of ways of sitting such that two newly-weds are always together is 2! * 7! (=10080). Subtracting gives 30240.
(c) Easy. Six people are left and they can sit in 6! = 720 ways.

@statusnet
Now you see that even newly-weds can spoil a good show. So mind the way you treat your sweetheart for I'm sure the cocky husband started that argument. smiley
Re: Nairaland Mathematics Clinic by statusnet(m): 10:49am On Oct 31, 2013
smurfy:

Good try statusnet. You got (c) right.

Here goes...
(a) Each couple as a unit can sit in 2! ways and each of the four two-unit couples can sit in 4! ways. That gives 48.

(b) 8! - (2! * 7!). Total number of ways of sitting without restriction is 8! (=40320). Total number of ways of sitting such that two newly-weds are always together is 2! * 7! (=10080). Subtracting gives 30240.
(c) Easy. Six people are left and they can sit in 6! = 720 ways.

@statusnet
Now you see that even newly-weds can spoil a good show. So mind the way you treat your sweetheart for I'm sure the cocky husband started that argument. smiley

Please can you explain how you got this : 2! * 7!
Re: Nairaland Mathematics Clinic by Nobody: 10:57am On Oct 31, 2013
statusnet:

Please can you explain how you got this : 2! * 7!

Please note that the last NOT in question (b) was a mistake.

Here goes...
Two newly-weds must always sit together, i.e. 2!. There are now 7 'people'. So they all can sit in 2! * 7! ways.
It's like doing a P(X>2) = 1 - [P(0) + P(1)].
Re: Nairaland Mathematics Clinic by rhydex247(m): 11:54am On Oct 31, 2013
Here is my question.
1). The linear map H:R^3---->R^3 defined by H(x,y,z)=(x+y-2z, x+2y+z, 2x+2y-3z). Is H non singular?. Find the formula for H^-1 and hence evaluate H^-1(1,2,3).
Re: Nairaland Mathematics Clinic by dcitizen1: 1:35pm On Oct 31, 2013
The five star general approach to the problem: cos@+cos2@+ cos3@+

Let C = cos@ +cos2@ +cos3@+

Let S= sin@+sin2@+sin3@+ ( dat is the complex number by of the expression)

C+iS= (cos@ +isin@) (cos2@+isin2@)+ (cos3@ +isin3@)+

Thus, C+iS=e^i@+e^i2@ +ei3@+

C+iS=e^i@/(1 -ei@)(using sum to infinity)

C+is= e^i@ * (1-e^-i@)/(1-e^i@)(1-e^-i@)

C+is= e^i@-1/2-e^i@-e^-i@

C+iS=cos@+isin@-1/2(1-cos@)

Taking the real part of the expression

Cos@+cos2@+cos3@ = cos@-1/2(1-cos@)
Re: Nairaland Mathematics Clinic by Nobody: 2:22pm On Oct 31, 2013
Mathematics is sacred.
Re: Nairaland Mathematics Clinic by Laplacian(m): 2:22pm On Oct 31, 2013
rhydex 247: Here is my question.
1). The linear map H:R^3---->R^3 defined by H(x,y,z)=(x+y-2z, x+2y+z, 2x+2y-3z). Is H non singular?. Find the formula for H^-1 and hence evaluate H^-1(1,2,3).
...u have not provided d solutn 2 one of ur questins, DESCRIBE 'W' IN TERMS OF ITS DIMENSION...
Let p=x+y-2z.....
.......q=x+2y+z....
........r=2x+2y-3z....
From, the abov eqns we deduc dat x=5r-8p-q,
y=q-3r+5p,
z=r-2p....
So that the map H is invertibl afterall, moreover,
H^-1(p,q,r)=(5r-8p-q, q-3r+5p, r-2p)
...H^-1(1,2,3)=(5, -2, 1)
Re: Nairaland Mathematics Clinic by jackpot(f): 3:46pm On Oct 31, 2013
d citizen:
The five star general approach to the problem: cos@+cos2@+ cos3@+

Let C = cos@ +cos2@ +cos3@+

Let S= sin@+sin2@+sin3@+ ( dat is the complex number by of the expression)

C+iS= (cos@ +isin@) (cos2@+isin2@)+ (cos3@ +isin3@)+

Thus, C+iS=e^i@+e^i2@ +ei3@+

C+iS=e^i@/(1 -ei@)(using sum to infinity)
Hi Sir d citizen, first of all, I must start by acknowledging your mathematical prowess and ability to think critically.

But I hope you know that the formula for the sum to infinity of a GP is valid if only absolute value of the common ratio is less than 1; i.e., |r|<1.

But it is easy to see that the GP
ei@, e2i@, e3i@, . . .
has common ratio r= ei@
and its absolute value is
|r|=|ei@|=|cos@+i sin@|
=sqrt{cos2@+sin2@}=1
and as such, applying the sum to infinity of a GP there is extremely fallacious. wink

Consequently, I'm afraid that your solution is wrong.
C+is= e^i@ * (1-e^-i@)/(1-e^i@)(1-e^-i@)

C+is= e^i@-1/2-e^i@-e^-i@

C+iS=cos@+isin@-1/2(1-cos@)


Taking the real part of the expression

Cos@+cos2@+cos3@ = cos@-1/2(1-cos@)
Granted, your solution is already wrong. Now your rationalization(as shown in the bolded) here is also wrong since
e^i@/(1-e^i@)= -1+1/(1-e^i@)
=-1 + 1/{(1-cos@)-i sin@}
=-1+{(1-cos@)+i sin@}/{(1-cos@)2+sin2@}
=-1+{(1-cos@)+i sin@}/{2(1-cos@)}
and if you take the real part of this, you should be able to get
-1+ (1-cos@)/2(1-cos@)
=-1+1/2
=-1/2


My Regards cool cool cool cool kiss



I remain
your humble servant-ress wink

JACKPOT cheesy

3 Likes

Re: Nairaland Mathematics Clinic by dcitizen1: 5:02pm On Oct 31, 2013
@jackpot,

Look closely at ur rationalisation, u will see an error there

-1+1/1-(cos@+isin@)

It is wrongly equated and rationalised.

Again, in ur elementary sum to infinity,

The r is not a modulus. It is an ordinary r dat is less than 1 not its absolute value

Let me give u an example if u have r= -1 as ur common ratio, then d modulus, is equal to 1, which go contrary to the principle of geometric series to infinity.
. I will like the person dat pose the questions to confirm if my answer is wrong. Although, i am solving d problem with my fone. I am certain dat the answer is right
Re: Nairaland Mathematics Clinic by Laplacian(m): 5:12pm On Oct 31, 2013
jackpot:
Hi Sir d citizen, first of all, I must start by acknowledging your mathematical prowess and ability to think critically.

But I hope you know that the formula for the sum to infinity of a GP is valid if only absolute value of the common ratio is less than 1; i.e., |r|<1.

But it is easy to see that the GP
ei@, e2i@, e3i@, . . .
has common ratio r= ei@
and its absolute value is
|r|=|ei@|=|cos@+i sin@|
=sqrt{cos2@+sin2@}=1
and as such, applying the sum to infinity of a GP there is extremely fallacious. wink

Consequently, I'm afraid that your solution is wrong.
Granted, your solution is already wrong. Now your rationalization(as shown in the bolded) here is also wrong since
e^i@/(1-e^i@)= -1+1/(1-e^i@)
=-1 + 1/{(1-cos@)-i sin@}
=-1+{(1-cos@)+i sin@}/{(1-cos@)2+sin2@}
=-1+{(1-cos@)+i sin@}/{2(1-cos@)}
and if you take the real part of this, you should be able to get
-1+ (1-cos@)/2(1-cos@)
=-1+1/2
=-1/2


My Regards cool cool cool cool kiss



I remain
your humble servant-ress wink

JACKPOT cheesy
...Hi Lady Jackpot, if there's is anyone worth recommendation, i think u should be a good candidate, for ur intricacy&ingenuity...
I'll start by pointin out 2 u dat, d citizen's rationalization approach is a100% as valid as urs...u both obtained d same result, though his inconsitent use of bracket makes his wrk luks ambiguous...cancel out 1-cos@ from his final result & u'll obtain urs...i'll leav dat as an oversight on ur part...as regardin |r|=1, it only implies that d series is not ABSOLUTELY CONVERGENT, now we can all show dat d series is CONDITIONALLY CONVERGENT...and dat vindicates d citizen's result...
Re: Nairaland Mathematics Clinic by Laplacian(m): 5:21pm On Oct 31, 2013
d citizen:
@jackpot,

Look closely at ur rationalisation, u will see an error there

-1+1/1-(cos@+isin@)

It is wrongly equated and rationalised.

Again, in ur elementary sum to infinity,

The r is not a modulus. It is an ordinary r dat is less than 1 not its absolute value

Let me give u an example if u have r= -1 as ur common ratio, then d modulus, is equal to 1, which go contrary to the principle of geometric series to infinity.
. I will like the person dat pose the questions to confirm if my answer is wrong. Although, i am solving d problem with my fone. I am certain dat the answer is right

@d citizen,
her rationalization approach is error-free, i suggest u use brackets in ur solutions to avoid ambiguity....
...though ur answer is correct but ur 'argument' does not justify u because ur transition (cos@) to d complex domain (e^i@) also changes d condition r<1 to |r|<1...
Re: Nairaland Mathematics Clinic by dcitizen1: 5:28pm On Oct 31, 2013
@ laplacian,

I like ur clarification dat u add to d questioning and venting of my approach to the work by jackpot. Well, my inconsistent use of bracket is due to the fact dat i am using my nokia e63 to type the math problem and my busy schedule at work and i have left math since 2007 after graduation. However, i am damn sure dat i got d answer and approach right. Thank you once again for ur clarification. I get what u mean now.

2 Likes

Re: Nairaland Mathematics Clinic by Mbahchiboy(m): 7:16pm On Oct 31, 2013
Mbahchiboy: TO MY GENERALS:MAKE UNA DO DIS 1 4 ME::
if S=a(r^n-1)/r-1....
make r d subject of d formular
still pending.....plz i need answers to dis

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