Q71. Which formula correctly represents the sum of the first n terms of an arithmetic series (Sn), where a is the first term and d is the common difference?Mathematics — NUST Mock 2 — Question 71 of 200A. Sn = n/2 [2a + (n-1)d]B. Sn = n/2 [a + (n-1)d]C. Sn = n/2 [2a + (n+1)d]D. Sn = n/2 [2a + 1]Practice more Mathematics MCQs for entrance exam preparation on Examora.io.← Previous Question Next Question →