Question

If the sum of first 7 terms and 15 terms of an A.P are 98 and 390 respectively then find sum of first 10 terms​

Answer 1

Answer:

Step-by-step explanation:

Hope this answer will help you

Answer 2

Step-by-step explanation:

a=5 and d=3 n=10

S10=10/2 (2×5+(10-1)3)

S10=5 (10+9×3)

S10=5 (10+27)

S10=5×37

S10=185