Binomial Theorem

  • Thread starter Caldus
  • Start date
  • #1
106
0
I get a number that is too big when I calculate the coefficient of x^25 in:

(2x - (3/x^2))^58

This is how I found the coefficient:

Code:
Note that (58) = A combination value...
           k

(58) * (2x)^(58-k) * (-3/x^2)^k
 k
(58) * (2)^(58 - k) * (x)^(58 - k) * (-3)^k * (1/x^2)^k
 k
(58) * (2)^(58 - k) * (-3)^k * (x)^(58 - k) * (x)^-2k
 k
(58) * (2)^(58 - k) * (-3)^k * (x)^(58 - 3k)
 k

58 - 3k = 25
-3k = -33
k = 11

So:

(58) * 2^47 * (-3)^11 * (x)^25
 11

This comes out to be a gigantic number. So I am unsure whether it is anywhere close to being correct despite that I thought that I followed the steps correctly. : \
 

Answers and Replies

  • #2
591
0
Thats the right answer; -5676647367067636376814212874240
 

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