If the sum of the first ‘n’ terms of an A.P. is 5n + n^2 then find its 10th term
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If the sum of the first ‘n’ terms of an A.P. is 5n + n^2 then find its 10th term
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Answer:
a10 = 24
Step-by-step explanation:
sum of n terms = 5n + n²
first term = s1 = a1
a1 = 5(1) + 1²
= 5 + 1
= 6
sum of two terms = s2 = a1 + a2
= 5(2) + 2²
= 10 + 4
= 14
a1 + a2 = 14
6 + a2 = 14
a2 = 14 - 6
a2 = 8
d = a2 - a1
d = 8 - 6
d = 2
10th term = a + (n - 1) d
a10 = 6 + (10 - 1)(2)
a10 = 6 + (9 × 2)
a10 = 6 + 18
a10 = 24
Hope you get your answer