Помогите с логарифмами, очень срочно

7.
$log_{4}500= \frac{log_{3}500}{log_{3}4}= \frac{log_{3}(5^2*20)}{log_{3}(20:5)}= \frac{log_{3}5^2+log_{3}20}{log_{3}20-log_{3}5}= \\ \\ = \frac{2log_{3}5+log_{3}20}{log_{3}20-log_{3}5}= \frac{2b+a}{a-b}= \frac{a+2b}{a-b}$

8.
$log_{9}(-2x-2) \leq - \frac{1}{2} \\ \\ -2x-2\ \textgreater \ 0 \\ -2x\ \textgreater \ 2 \\ x\ \textless \ -1$

$-2x-2 \leq 9^{- \frac{1}{2} } \\ -2x-2 \leq (3^2)^{- \frac{1}{2} } \\ -2x-2 \leq 3^{-1} \\ -2x \leq \frac{1}{3}+2 \\ -2x \leq 2 \frac{1}{3} \\ -2x \leq \frac{7}{3} \\ x \geq - \frac{7}{6}$
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x∈[-7/6; -1)