Question

Calculati: 2×(1+2+3²+.....+3⁴⁹)​

Answer 1

Răspuns:

$2 \times (1 + 3 + {3}^{2} + ..... + {3}^{49} ) = 2 \times x\\ 1 + 3 + {3}^{2} + ..... + {3}^{49} =x \\ \times 3 \\ 3 + {3}^{2} + ..... + {3}^{50} = 3x \\ - \\ ({3}^{50} - 1) \div 3 = x \\ ({3}^{50} - 1) \div 3 \times 2 = \\ {3}^{49} \times 2 - 2 \div 3 =$