Final answer:
The option √x + 3 = 13 is the radical equation among the given choices, as it contains the variable x under a square root, which defines a radical equation.
Step-by-step explanation:
The question involves identifying which of the given options is a radical equation. A radical equation is an equation where the variable is under a radical sign, most commonly a square root. Looking at the options provided, the one that fits this description is √x + 3 = 13, as it has the variable x under a square root.
We recognize a radical equation since it involves a variable within the radical, and solving it usually requires isolating the radical on one side and then raising both sides of the equation to the power that matches the root to eliminate the radical. Hence, the process of solving radical equations could involve squaring both sides to clear a square root.
In summary, a radical equation is an equation where the variable is contained within a radical.