Answer :
To find the value of the polynomial [tex]x^6 - 19x^5 + 69x^4 - 151x^3 + 229x^2 + 166x + 26[/tex] at [tex]x = 15[/tex] without substituting, we can use an alternative approach such as examining the polynomial for potential simplifications or patterns, or applying known mathematical theorems, such as Vieta's formulas or synthetic division, if they help in a specific context.
However, in this case, the most straightforward and direct method typically involves substitution, which is mentioned as a constraint not to perform. Therefore, based on the information given and the requirement to avoid direct substitution, it suggests highlighting the fact that polynomial evaluation often involves substitution directly or indirectly, and any solution using a different method may involve deeper algebraic insights.
Since of this nature, one might ordinarily expect it's a high school-level problem where substitution is standard practice. Nevertheless, any other method would likely require more advanced treatments or additional conditions for factoring or transformations to simplify the expression effectively.
Thus, it’s important to rely on fundamental algebraic understanding if substitution is not an option, as no alternative simplification or theorem directly applies with the information provided.