\[\boxed{\text{4}\text{1}\text{\ (41).\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[1)\ \frac{6}{b - 4} = \frac{6 \cdot 5}{(b - 4) \cdot 5} = \frac{30}{5b - 20}\]
\[2)\ \frac{6}{b - 4} = \frac{6 \cdot ( - 3)}{(b - 4) \cdot ( - 3)} =\]
\[= \frac{- 18}{- 3b + 12} = \frac{- 18}{12 - 3b}\]
\[3)\ \frac{6}{b - 4} = \frac{6 \cdot b}{(b - 4) \cdot b} = \frac{6b}{b^{2} - 4b}\]
\[4)\ \frac{6}{b - 4} = \frac{6 \cdot (b + 4)}{(b - 4)(b + 4)} =\]
\[= \frac{6b + 24}{b^{2} - 16}\]