1.

Find S² for an A.p 3,5,7 ,9​

Answer»

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 !!!!!!!


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