[tex]2^{x} + 2^{x} \times 2^{1} + {2}^{x} \times {2}^{2} + {2}^{x} \times {2}^{3} = {2}^{x} (1 + 2 + 4 + 8) = {2}^{x} \times 15\\ {2}^{x} = 30 \div 15 \\ {2}^{x} = 2 \\ x = 1[/tex]
