Question

sum of 20 terms of 3 + 6 + 12 + so on​

Answer 1

Step-by-step explanation:

a = 3 , r = 2

S(20) = a(rⁿ - 1)/(r - 1)

= 3 (2^20 - 1)/(2 - 1)

= 3 (2^20 - 1) / 1

= 3 (10,48,576 - 1)

= 3 × 10,48,575

= 31,45,725