The sum of n terms of an A.P is 3n²+5n²,then which term will be 164 ?
Answers
Answered by
2
Answer:
Answer.
S = 3n2 + 5n S1 = a1 = 3+5 = 8 S2 = a1 + a2 =6+10 =16 ⇒a2 = 8 S3 = a1 + a2 + a3 = 9 + 15 = 24 ⇒a3 = 8 ∴ AP is 8,8,8,..... Thus a =8 , d=0 Sm = 164 Sum of AP = n/2 [2a + (n-1)d] 164 = m/2 [2(8) + (m-1)0] 164 = m/2[16+0] 164 = m * 16 / 2 m = 164 * 2 /16 m = 20.5
Similar questions