Question

In an A.P a=8,tn=62,Sn=210,Find n​

Answer 1

Step-by-step explanation:

Sn =

$\frac{n}{2} (a + tn) \\ 210 = \frac{n}{2} (8 + 62) \\ \\ 210 = \frac{n}{2} (70) \\ \\ 210 = n \times 35 \\ \\ \\ n = 6$