Find the coefficient of

๐‘ฅ3
๐‘–๐‘› ๐‘กโ„Ž๐‘’ ๐‘’๐‘ฅ๐‘๐‘Ž๐‘›๐‘ ๐‘–๐‘œ๐‘› ๐‘œ๐‘“ 1
1+๐‘ฅ
A. -1
B. -6
C. 1
D. 6

1 answer

We can use the binomial theorem to expand the expression:

(1 + x)^1 = 1 + 1x

(1 + x)^2 = 1 + 2x + 1x^2

(1 + x)^3 = 1 + 3x + 3x^2 + 1x^3

So, the coefficient of ๐‘ฅ^3 in the expansion of (1 + ๐‘ฅ)^1 is 0, and the coefficient of ๐‘ฅ^3 in the expansion of (1 + ๐‘ฅ)^2 is also 0. The coefficient of ๐‘ฅ^3 in the expansion of (1 + ๐‘ฅ)^3 is 1. Therefore, the answer is:

C. 1