If the coefficient of xr x^r xr in the expansion of (1+x+x2)100 (1 + x + x^2)^{100} (1+x+x2)100 is ar a_r ar, and S=∑r=0300ar S = \sum\limits_{r=0}^{300} a_r S=r=0∑300ar, then
∑r=0300rar= \sum\limits_{r=0}^{300} r a_r = r=0∑300rar=
Given below are two statements, one is labelled as Assertion (A) and the other one labelled as Reason (R).Assertion (A): 1+2.13.2+2.5.13.6.4+2.5.8.13.6.9.8+…∞=4 1 + \frac{2.1}{3.2} + \frac{2.5.1}{3.6.4} + \frac{2.5.8.1}{3.6.9.8} + \dots \infty = \sqrt{4} 1+3.22.1+3.6.42.5.1+3.6.9.82.5.8.1+…∞=4 Reason (R): ∣x∣<1,(1−x)−1=1+nx+n(n+1)1.2x2+n(n+1)(n+2)1.2.3x3+… |x| <1, \quad (1 - x)^{-1} = 1 + nx + \frac{n(n+1)}{1.2} x^2 + \frac{n(n+1)(n+2)}{1.2.3} x^3 + \dots ∣x∣<1,(1−x)−1=1+nx+1.2n(n+1)x2+1.2.3n(n+1)(n+2)x3+…