MOAR!!!!! binominals (1 Viewer)

[shuning]

When is expanded in increasing powers of x, it is found that the coefficients of and have the same value. find the value of n and show that the 2 coefficients mentioned are greater than all other coefficients in the expansion


i got n =23 ( would be nice if u can check for me if i got correct or not... cuz i dont have the answers. )

But how do i do the 2nd part?

 

[lyounamu]

When is expanded in increasing powers of x, it is found that the coefficients of and have the same value. find the value of n and show that the 2 coefficients mentioned are greater than all other coefficients in the expansion


i got n =23 ( would be nice if u can check for me if i got correct or not... cuz i dont have the answers. )

But how do i do the 2nd part?

i believe that n = 14

for the 2nd part, u just have to show that the max coefficient occurs at those 2

for example:

i will just use this 'formula" since i am lazy to actually derive it here:

(n-r+1)/r x b/a >1
15-r/r x 2/3 > 1
30-2r > 3r
30 >5r
r < 6
also check with r = 5 and stuff.

highest coefficient 1260971712 for the referec
so ye.

 

[lyounamu]

using n=23 doesn't work out tho

coefficient of x^6 is givenby

nC6 3^(n-6) 2^6

and coefficient of x^5 is given by

nC5 3^(n-5) 2^5

so equate them

and work it out.

 

[clintmyster]

using n=23 doesn't work out tho

coefficient of x^6 is givenby

nC6 3^(n-6) 2^6

and coefficient of x^5 is given by

nC5 3^(n-5) 2^5

so equate them

and work it out.

oh I see yes. What shunnings and I did was totally forget the 2, the coefficient of the x and the fact that it is changing as well. Thanks namu.

 

[shuning]

回复: Re: MOAR!!!!! binominals

oh I see yes. What shunnings and I did was totally forget the 2, the coefficient of the x and the fact that it is changing as well. Thanks namu.

hehehe some1 did it the same why as i did :rofl:

 

[shuning]

回复: Re: MOAR!!!!! binominals

thanks namu