Coefficient of x100in1+(1+x)+(1+x)2+(1+x)3…(1+x)n is 201C101,(n>100) then n =
100
200
101
none of these
Coefficient of x100=100C100+101C100+…+nC100=n+1C101=201C101⇒n=200
If |x| < 1 then the coefficient of xn in the expansion
of (1+x+x2+.......)2 will be