Question

Não consigo resolver esta questão

Answer 1

$\frac{a^{n+4}-a^3\cdot\,a^n}{a^4\cdot\,a^n}=\\\\\frac{a^4\cdot\,a^n-a^3\cdot\,a^n}{a^4\cdot\,a^n}=\\\\\frac{a^3\cdot\,a^n(a^1-a^0)}{a^4\cdot\,a^n}=\\\\\boxed{\frac{(a-1)}{a}}$