4) Simplify \( \frac{c^3+c^5}{c^7+c^5} \).

\( \frac{c^3+c^5}{c^7+c^5} = \frac{c^3(1+c^2)}{c^5(c^2+1)} = \frac{c^3}{c^5} = \frac{1}{c^2} \), provided \( c \neq 0 \).