Question

find s3 for the A.P 3,5,7,9
10
24
17
15​

Answer 1

Answer:

d = 5-3= 2

a = 3

n = 3

s3 = n/2[2a+(n-1)d]

= 3/2[2×3 + (3-1)2]

= 3/2[6 + 4]

= 3/2 × 10

= 3×5

= 15

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Answer 2

Answer:

15

step by step explanation

a=3 , d = 5-3= 2

sn = n/2 ( 2a + (n-1)d

s3 = 3/2 (2×3 + ( 3-1 )2

= 3/2 ( 6 +4 )

= 3/2 × 10

= 15