1. The problem is to understand why $x^3$ is not the leading term in the polynomial $x^5 + x^3 - x + 5$. 2. The leading term of a polynomial is the term with the highest exponent of $x$. 3. In the polynomial $x^5 + x^3 - x + 5$, the exponents are 5, 3, 1, and 0 respectively. 4. Since 5 is greater than 3, 1, and 0, the term $x^5$ has the highest power. 5. Therefore, $x^3$ is not the leading term because its exponent 3 is less than 5. 6. The leading term determines the end behavior and size of the polynomial for large $|x|$ values, so $x^5$ dominates over $x^3$ as $x$ grows large.