" 23."son3+7+13+21+31+..." के "n" प्दो का योग जात कीजिए। "

Find the value of 2.1 + 2.25 div [63-{7.5xx8+ (13-2.5xx5)}] . 2.1 + 2.25 div [63-{7.5xx8+ (13-2.5xx5)}] का मान ज्ञात कीजिए।

Find the sum of the series 3 + 7 + 13 + 21 + 31 + … to n terms . Find the sun when n=20

Find the sum of the series 3 + 7 + 13 + 21 + 31 + … to n terms . Find the sun when n=20