\[\boxed{\text{204\ (204).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
Пояснение.
Решение.
\[1)\ m^{5} \cdot m^{4} = m^{5 + 4} = m^{9}\]
\[2)\ x \cdot x^{2} = x^{1} \cdot x^{2} = x^{1 + 2} = x^{3}\]
\[3)\ a^{3} \cdot a^{3} = a^{3 + 3} = a^{6}\]
\[4)\ 6^{8} \cdot 6^{3} = 6^{8 + 3} = 6^{11}\]
\[5)\ y^{3} \cdot y^{5} \cdot y^{9} = y^{3 + 5 + 9} = y^{17}\]
\[6)\ c^{8} \cdot c^{9} \cdot c = c^{8 + 9 + 1} = c^{18}\]
\[7)\ (b - c)^{10} \cdot (b - c)^{6} =\]
\[= (b - c)^{10 + 6} = (b - c)^{16}\]
\[8)\ 11^{2} \cdot 11^{4} \cdot 11^{6} = 11^{2 + 4 + 6} =\]
\[= 11^{12}\]
\[9)\ x^{4} \cdot x \cdot x^{11} \cdot x^{2} = x^{4 + 1 + 11 + 2} =\]
\[= x^{18}\]
\[10)\ \left( \text{ab} \right)^{5} \cdot \left( \text{ab} \right)^{15} = \left( \text{ab} \right)^{5 + 15} =\]
\[= \left( \text{ab} \right)^{20}\]
\[11)\ (2x + 3y)^{6} \cdot (2x + 3y)^{14} =\]
\[= (2x + 3y)^{6 + 14} = (2x + 3y)^{20}\]
\[12)\ ( - xy)^{2} \cdot ( - xy)^{7} \cdot ( - xy)^{9} =\]
\[= ( - xy)^{2 + 7 + 9} = ( - xy)^{18}\]