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