Find the `20^(t h)`term from the last term of the AP : 3, 8, 13, . . , 253.

Answer

N/a

Explanation

Here a=3, d=8-3=13-8=5, n=20
`because" "S_(n)=(n)/(2)[2a+(n-1)d]`
`rArr " "S_(20)=(20)/(2)[2xx3+(20-1)xx5]`
`=10(6+95)=1010.`