An AP 5, 8, 11…has 40 terms. Find the last term. Also find the sum of the last 10 terms.
First Term of the AP (a) = 5
Common difference (d) = 8 - 5 = 3
Last term
= `"a"_40` = a + (40 - 1) d
= 5 + 39 × 3 = 122
Also `a_31` = a + 30d = 5 + 30 × 3 = 95
Sum of last 10 terms = `"n"/2`(`"a"_31` + `"a"_40`)
= `10/2` (95 + 122)
= 5 × 217 = 1085