0,b<0\\\\\sqrt{121\, a^{16}\, b^{10}}=11\cdot |a|^8\cdot |b|^5=11\cdot a^8\cdot (-b)^3=-11a^8b^3" alt="1)\; \; a<0\; ,\; \; b<0\\\\\sqrt{\frac{a^{10}}{16b^6}}=\frac{|a|^5}{4|b|^3}=\frac{(-a)^5}{4\, (-b)^3}=\frac{-a^5}{-4b^3}=\frac{a^5}{4b^3}\\\\2)\; \; a>0,b<0\\\\\sqrt{121\, a^{16}\, b^{10}}=11\cdot |a|^8\cdot |b|^5=11\cdot a^8\cdot (-b)^3=-11a^8b^3" align="absmiddle" class="latex-formula">