The sum of n terms of an A.P. is 14n2 + 10n. Find its 10th term.
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Answer:
276
Step-by-step explanation:
Sn = (n/2)[2a+(n-1)d] = 14n²+10n
S1 = a = 14(1²)+ 10(1) = 24----(i)
S10 = (10/2)[2a+(10-1)d]
14(10²)+10(10) = 5(2a+9d)
=> 2a+9d =300----(ii)
from (i) and (ii),
a +9d = 300-24 = 276
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