Assertion: 2 + 4 + 6 + 8 + ... + 50 = 650 Reason: Sum of n terms of A.P. n/2[2a + (n - 1)d].

Question

KollegeApply · Accepted Answer

Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A). Explanation: a = 2, d = 2 and l = 50 n = 50 = 2 + (n − 1)2 $\Rightarrow$ 50 − 2 = (n − 1)2 $\Rightarrow$ 48 = (n − 1)2 $\Rightarrow$ $\frac{48}{2}$ = n − 1 $\Rightarrow$ 24 + 1 = n $\Rightarrow$ n = 25 S_n = n/2[2a + (n - 1)d] `S_25 = $\frac{25}{2}$[2(2) + (25 - 1)2] S_25 = $\frac{25}{2}$[4 + (24)2] S_25 = $\frac{25}{2}$[4 + 48] S_25 = $\frac{25}{2}$[52] S_25 = 25 $\times$ 26` S25 = 650

AChoose Your Answer