Ответ:
Используем свойства степеней: \(a^r\cdot a^s=a^{r+s}\), \(a^r:a^s=a^{r-s}\).
- \(a^3\cdot a^4\cdot a^{12}=a^{19}\).
- \(a^{2/3-5/4-1/2+2/5}=a^{-41/60}=\dfrac1{a^{41/60}}\).
- \(a^{-1/2+3/2+1}b^{1-3/4-15/4}=a^2b^{-7/2}=\dfrac{a^2}{b^{7/2}}\).
- \(a^{-2+3-5}=a^{-4}=\dfrac1{a^4}\).
- \(b^{4+1/4+3/5+1/2}=b^{107/20}\).
- \(a^{3/2-7/4}b^{-1/2-15/8}=a^{-1/4}b^{-19/8}=\dfrac1{a^{1/4}b^{19/8}}\).
- \(a^{1-1/3}b^{7/6-2/3}=a^{2/3}b^{1/2}\).
- \(\sqrt[3]{81x^4y/(3xy)}=\sqrt[3]{27x^3}=3x\).
- \(\dfrac{\sqrt{(\sqrt{10}-2)(\sqrt{10}+2)}}{\sqrt{24}}=\sqrt{6/24}=1/2\).
- \(x^3-2x^2-9x+18=(x-2)(x-3)(x+3)\), поэтому результат \(x-3\).
- \(\dfrac{10\cdot2^n}{2^{n-1}(4+1)}=4\).
- \(\dfrac{\sqrt{54}}{\sqrt{(\sqrt{15}+3)(\sqrt{15}-3)}}=\dfrac{\sqrt{54}}{\sqrt6}=3\).
- \(\dfrac{9x^{-6}}{4x^{-6}}=\dfrac94\).
- \(\dfrac{(a-3)(a+3)}{(a-3)(b+4)}=\dfrac{a+3}{b+4}\).
- \(\dfrac{2^{n+2}(1-2)}{6^{n+1}7^{n+2}}=-\dfrac{2^{n+2}}{6^{n+1}7^{n+2}}\).
- \(\dfrac{(5x+2)(x-1)}{x(5x+2)}=\dfrac{x-1}{x}\).
- \(\dfrac{m}{(m-1)^2}-\dfrac{m+2}{(m+2)(m-1)}=\dfrac{m-(m-1)}{(m-1)^2}=\dfrac1{(m-1)^2}\).
- \(\dfrac{(3^2\cdot5)^n}{3^{2n-1}5^{n-2}}=3\cdot5^2=75\).
Ответ: 1) \(a^{19}\); 2) \(a^{-41/60}\); 3) \(a^2/b^{7/2}\); 4) \(a^{-4}\); 5) \(b^{107/20}\); 6) \(a^{-1/4}b^{-19/8}\); 7) \(a^{2/3}b^{1/2}\); 8) \(3x\); 9) \(1/2\); 10) \(x-3\); 11) 4; 12) 3; 13) \(9/4\); 14) \((a+3)/(b+4)\); 15) \(-2^{n+2}/(6^{n+1}7^{n+2})\); 16) \((x-1)/x\); 17) \(1/(m-1)^2\); 18) 75.
