Question

Решите неравенство:
2/(7^x - 7) ≥ 5/(7^x - 4)

Answer 1

ОДЗ
$7^x \neq 7 \\ \\ x \neq 1 \\ \\ 7^x \neq 4 \\ \\ x \neq log_74$


$\frac{2}{7^x - 7} \geq \frac{5}{7^x - 4} \\ \\ \frac{2}{7^x - 7} - \frac{5}{7^x - 4} \geq 0 \\ \\ \frac{2*(7^x-4)-5(7^x-7)}{(7^x - 7)(7^x-4)} \geq 0 \\ \\ \frac{2*7^x-8-5*7^x+35}{(7^x - 7)(7^x-4)} \geq 0 \\ \\ \frac{-3*7^x+27}{(7^x - 7)(7^x-4)} \geq 0 \\ \\ \frac{-3*(7^x-9)}{(7^x - 7)(7^x-4)} \geq 0 \\ \\ \frac{7^x-9}{(7^x - 7)(7^x-4)} \leq 0$

\\\\\\\\\\\\\\\\\\\\\\\\\\\\                                  \\\\\\\\\\\\\\\\\\\\\        
            -                                   +                    -                               + 
______________log₇4_________1__________log₇9______

x∈(-∞; log₇4)∪(1; log₇9]