Question

a=3 d=3 n=12 find sn

Answer 1

given , first term 'a = 3

and common difference (d ) = 3
and ' n = 12

sum =Sn = n /2 ( 2a + ( n - 1 ) d ),put ,n = 12

S12 = 12 /2 ( 2×3 + ( 12 - 1 ) 3 )

S12 = 6 ( 6+ ( 11 ) 3 )

S12 = 6 ( 6+ 33 )

S12 = 6 × 39

S12 = 234
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Your Answer: S12 = 234
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Answer 2

here ,

a=3
d=3

& n=12


Sn=n/2{2a+(n-1)d}

6{6+33)

39×6

234