Question

एका अंकगणिती श्रेढिचे 11 वे पद 16 आणी 21 वे पद 29 आहे तर त्या श्रेढिचे 41 वे पद काढा?

Answer 1

lets assume first term is a and common difference is d

nth term is given as

Tn = a + (n-1)d

T11 = 16

T11 = a + (11-1)d

a + 10d = 16 (1)

T21= 29

T21 = a + (21-1)d

a + 20d = 29 (2)

subtracting eq 1 from 2

a+ 20d - a - 10d = 29-16

10d = 13

d = 13/10

putting this value in eq 2

a + 20×13/10 = 29

a+ 26 = 29

a = 29-26 = 3

so 41 term is

T41 = a + (41-1)d = 3 + 40d = 3 + 40 × 13/10 = 3 + 52 = 55