Find the value of `|(1 + i)/(1-i)|`

Answer

b

Explanation

`(x + C_(0)) (x + C_(1)) (x + X_(2)) + …+ (x + C_(n)) `
` = x^(n+1) + (sum_(r=0)^(n) C_(r))^(n) + ( underset(0 le i j le n )(sumsum)C_(i) C_(j)) x^(n-1) + ... `
` therefore ` Coefficient of ` x^(n-1) " in" underset(0 le i j le n )(sumsum)C_(i) C_(j)`
`= (1)/(2){ (sum_(r=0)^(n) C_(r))^(2) - ( sum_(r=0)^(n) C_(r)^(2) )} = (1)/(2) = { 2^(2n) - ""^(2n)C_(n)} `
` = 2^(2n-1)- (1)/(2) . ""^(2n)C_(n) ` .