Question

calculați ecuatia: 4+4^2+4^3+...+4^72​

Answer 1

$4 + {4}^{2} + {4}^{3} + ... + {4}^{72} = \\ = 4 \times (1 + 2 + 3 + ... + 18) = \\ = 4 \times (18 \times 19 \div 2) = \\ = 4 \times (342 \div 2) = \\ = 4 \times 171 = \\ = 684$