Question

Consider the expression (a + b)n.

According to the Binomial Theorem, the kth term in the expanded form of this expression (where k≤ n) is ;


A)
C(n, k)*xkyn-k
B)
C(n, k-1)*xkyn-k
C)
C(n-1, k)*xkyn-k
D)
C(n-1, k-1)*xkyn-k

Answer 1

The kth term (with 1 ≤ k ≤ n) should be \[C(n,k-1)x^{k-1}y^{n-k+1}\]
But this answer is not in the multiple choices.

Answer 2

Notice that this is for the expansion of (x+y)n. For (a+b)n you would have:
\[C(n,k-1)a^{k-1}b^{n-k+1}\]