Выполните вычитание 42/(b^2+7b)-6/b.

\[\frac{42}{b^{2} + 7b} - \frac{6}{b} = \frac{42}{b(b + 7)} - \frac{6^{\backslash b + 7}}{b} =\]

\[= \frac{42 - 6 \cdot (b + 7)}{b(b + 7)} = \frac{42 - 6b - 42}{b(b + 7)} =\]

\[= - \frac{6b}{b(b + 7)} = - \frac{6}{b + 7}\]