# The coefficient of

Question:

The coefficient of $x^{7}$ in the expression

$(1+x)^{10}+x(1+x)^{9}+x^{2}(1+x)^{8}+\ldots+x^{10}$ is :

1. 120

2. 330

3. 210

4. 420

Correct Option: , 2

Solution: