in an AP an =3n+2 then find 12th term
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EXPLANATION.
- GIVEN
An = 3n + 2
To find it's 12th term.
An = 3n + 2
put n = 1 we get,
3(1) + 2 = 5
put n = 2 we get,
3(2) + 2 = 8
put n = 3 we get,
3(3) + 2 = 11
put n = 4 we get,
3(4) + 2 = 14
Therefore,
series will be written as = 5,8,11,14 ......
Let first term = a = 5
common difference = d = b - a = 8 - 5 = 3
Formula of An term of Ap
An = a + ( n - 1 ) d
12th term = a + 11d
5 + 11(3)
5 + 33 = 38
Therefore,
12th term of Ap = 38
More information.
Formula of n terms of Ap
An = a + ( n - 1 ) d
Formula of sum of n terms of Ap
Sn = n / 2 ( 2a + ( n - 1 ) d)
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