Question

Решите систему уравнений: Log9 x-log9 y=1 Log4 (x+7y)=3

Answer 1

$log_{9}(x) - log_{9}(y) = 1 \\ log_{4}(x + 7y) = 3 \\ \\ log_{9}( \frac{x}{y} ) = 1 \\ log_{4}(x +7y) = 3 \\ \\ \frac{x}{y} = 9 \\ x + 7y = 12 \\ \\ x = 9y \\ x + 7y = 12 \\ \\ 9y + 7y = 12 \\ 16y = 12 \\ y = \frac{12}{16} = \frac{3}{4} \\ \\ x = 9 \times \frac{3}{4} = \frac{27}{4}$