C-13-Q119mediumsingle_mcqThe sum of the first 141414 terms of 3+9+27+⋯3 + 9 + 27 + \cdots3+9+27+⋯ is —a315−32\dfrac{3^{15} - 3}{2}2315−3b314−12\dfrac{3^{14} - 1}{2}2314−1c314−33^{14} - 3314−3d315+32\dfrac{3^{15} + 3}{2}2315+3ব্যাখ্যাWith a=3a=3a=3, r=3r=3r=3, n=14n=14n=14: S14=3(314−1)3−1=315−32S_{14}=\dfrac{3(3^{14}-1)}{3-1}=\dfrac{3^{15}-3}{2}S14=3−13(314−1)=.