Решение:
- \(\frac{(x^{-7})^{-6}}{x^{-3}} = \frac{x^{(-7) \cdot (-6)}}{x^{-3}} = \frac{x^{42}}{x^{-3}} = x^{42 - (-3)} = x^{42+3} = x^{45}\)
- \(x^{12} \cdot x^{-15} : x^{-7} = x^{12 + (-15)} : x^{-7} = x^{-3} : x^{-7} = x^{-3 - (-7)} = x^{-3+7} = x^4\)
- \(\frac{x^{-3} \cdot x^{-11}}{x^{-8}} = \frac{x^{-3 + (-11)}}{x^{-8}} = \frac{x^{-14}}{x^{-8}} = x^{-14 - (-8)} = x^{-14+8} = x^{-6}\)
- \(\frac{x^{-7}}{x^{-8} \cdot x^{13}} = \frac{x^{-7}}{x^{-8 + 13}} = \frac{x^{-7}}{x^5} = x^{-7 - 5} = x^{-12}\)
Ответ: а) x45; б) x4; в) x-6; г) x-12.