no of ways..

3 can be written as
1+1+1
2+1
1+2
3
(4 ways..)

In how many ways n can be written..
_________________
I think I posted this one earlier... in some post...(Nisahnt bhaiya gave the answer but not the method...that time...(sayad...jaha tak mujhe yaad hai))

(But later I solved it....and din' found that thread to post the solution so am starting a new thread.. :P)

so others may try this one....

20 Answers

11
Subash ·

i got a different method

n=1+1+.......n times

these ones can be grouped when you take all the ones together one way corresponding to nC0

so consider nC0+nC1+.....+nCn

but nC0 and nCn correspond to the same because in both cases we take all the 1s together

similar logic for all the other terms show that the expression has to be divided by two

so 2n-1

this time am i rite with my logic bhaiyya??

and bhaiyya the writing is on the screen[3]

62
Lokesh Verma ·

I mean if he wants to write
5=2+2+1

how will subash's method work!

33
Abhishek Priyam ·

deleted that...

33
Abhishek Priyam ·

[3] kk

62
Lokesh Verma ·

Priyam.. that is not for your..

I was asking Subash

21
tapanmast Vora ·

SIR can u xplain wat dus this mean ?

Then ho wdo you cover the cases by your method of having

2 groups of 2?

62
Lokesh Verma ·

Then ho wdo you cover the cases by your method of having

2 groups of 2?

11
Subash ·

it can also be given by nC0 because choosing no ones is equal to taking all the ones

nC2 is grouping 2 ones together

that is writing is as 2+n-2

62
Lokesh Verma ·

I appreciate your way of thinking but

I did not understand the method clearly

:(

why divided by 2?

Why is no of ways to chose all the 1's = nC0?? it should be nCn

What does nC2 stand for?

11
Subash ·

chek this up bhaiya!~

62
Lokesh Verma ·

hmm.. this was a nice question.. i remember :)

62
Lokesh Verma ·

Subash the writing is on the wall!

Just refer to what priyam wrote!

11
Subash ·

now how can i proceed????

62
Lokesh Verma ·

wow.. that is a method..

I love it priyam

Amazing :)

33
Abhishek Priyam ·

It is no of ways cutting the cake having n-1 slots...

2n-1
each slot has two option either to be cut or not...
no of slots = n-1
so 2n-1

33
Abhishek Priyam ·

great.. answer..:)

But isn't nC0+nC1+..nCn =2n

33
Abhishek Priyam ·

asan hai... just one line solution.... :P

1
Philip Calvert ·

why is this not in "p n c" is there some diff trick involved...?...

looks so much like..
sum of no of solutions of

a = n
a+ b = n
a +b +c =n
.
.
.
a +b + c + .. ...+(char)(n+97)= n (ASCII :D)

now please dont argue that this will only make sense for n <=26 :D

62
Lokesh Verma ·

yes

24
eureka123 ·

n belongs to natural nos. ???????

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