C-07-Q037mediumsingle_mcqThe nnn-th term of the geometric series a+ar+ar2+ar3+…a + ar + ar^2 + ar^3 + \ldotsa+ar+ar2+ar3+… is —aarnar^narnbarn−1ar^{n-1}arn−1ca+(n−1)ra + (n-1)ra+(n−1)rdarn−1\dfrac{a}{r^{n-1}}rn−1a