Question

given a = 3, n=8, S = 192, find d.​

Answer 1

Step-by-step explanation:

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

so,

192 = 8/2[ 2×3 + (8 - 1)d ]

=> 192 = 4 [ 6 + 7d ]

=> 192/4 = 6 + 7d

=> 6 + 7d = 48

=> 7d = 48 - 6

=> d = 42/7

hence, d = 6