If \(\displaystyle (1+x)^n=C_0+C_1x+C_2x^2+...+C_nx^n\), then the sum of the products of the coefficients taken two at a time can be represented by \[\sum_{i=0}^n \sum_{j=i+1}^{n}C_iC_j = 2^a - \frac{b!}{c(d!)^2}\] Then which of the following are correct?

- A: \(\ a=2n-1\)
- B: \(\ b=2n\)
- C: \(\ c=2\)
- D: \(\ d=n\)

Enter your answer as a 4-digit string of 1s and 9s \(-\) 1 for correct option, 9 for wrong. For example, 1199 indicates A and B are correct, C and D are incorrect. None, one or all may also be correct.

×

Problem Loading...

Note Loading...

Set Loading...