Final answer:
The leading coefficient in the given expression x^2 + 8x + 13 is 1, as it is the coefficient of the highest power term x^2.
Step-by-step explanation:
The leading coefficient in a polynomial expression is the coefficient of the term with the highest power of the variable. In the expression x^2 + 8x + 13, the term with the highest power of x is x^2. The coefficient of this term is 1, even though it is not explicitly written in front of the x^2. Therefore, the leading coefficient of the expression is 1.