Question

1 + 3 + 9 + 27 + ....... + 2187

Answer 1

`A=1+3+9+27+...+2187`

\(A=3^0+3^1+3^2+3^3+...+3^7\\ 3A=3^1+3^2+3^3+3^4+...+3^8\\ 2A=3^8-1\\ A=\left(3^8-1\right):2=3280\)

Answer 2

1 + 3 + 9 + 27 +... + 2187

=> 3⁰ + 3¹ + 3² + ...+ 3⁸

=> 3⁸ - 3¹

=> (3⁸ - 1) : 2

=> 3280