To solve the problem, follow these steps:
1. Identify the general term in the binomial expansion of \( \left( x^2 + \frac{2}{x} \right)^{15} \).
T_k = \binom{15}{k} (x^2)^{15-k} \left( \frac{2}{x} \right)^k
2. Simplify to find the term involving \( x \):
T_k = \binom{15}{k} x^{2(15-k)} \cdot \frac{2^k}{x^k} = \binom{15}{k} 2^k x^{30-3k}
3. Coefficient of \( x^{15} \):
Set the exponent \( 30-3k=15 \) to solve for \( k \):
30 - 3k = 15 \implies k = 5
Coefficient is:
\binom{15}{5}2^5=\frac{15!}{5! \cdot10!}\cdot32=96096
4. Independent term, constant term (no \( x \)):
Set the exponent \( 30-3k=0 \) to solve for \( k \):
30 - 3k = 0 \implies k = 10
Coefficient is:
\binom{15}{10}2^{10}=\frac{15!}{10! \cdot5!}\cdot1024=3075072
6. Ratio of coefficients:
\frac{96096}{3075072}=\frac{1}{32}
Thus, the ratio is:
\boxed{\frac{1}{32}}