find S² for an A.p 3,5,7 ,9
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Answered by
1
Answer:
576.
Step-by-step explanation:
a = 3
d = 2
l = 9 = an
an = a + ( n - 1 ) × d
9 = 3 + ( n - 1 ) × 2
9 - 3 = ( n - 1 ) × 2
6 ÷ 2 = ( n - 1 )
3 + 1 = n
n = 4
Sn = n/2 × [ 2a + ( n - 1 ) × d ]
Sn = 4/2 × [ (2 × 3) + (4 - 1) × 2 ]
Sn = 2 × [ (6) + (3) × 2 ]
Sn = 2 × (6 + 6)
Sn = 2 × 12
Sn = 24
So, S² = 24² = 576
Hope it helps u !!!!!!!
Answered by
2
Step-by-step explanation:
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