Final answer:
In the algebraic expression 5x + 17, the constant is 17. This is because it is the term in the expression that is not affected by the variable x and it does not change.
Step-by-step explanation:
The constant in the expression 5x + 17 is 17. A constant in algebra is a value that does not change and is not multiplied by a variable. In this expression, 5x represents a variable term, where 5 is the coefficient and x is the variable. The number 17 stands alone without a variable, making it the constant component of the expression. Constants are important as they can represent fixed values in equations and functions that we can use to solve for the variables.