You can replace t^2 with x in the equation t^2 = x, as both expressions represent the same value. This substitution is valid unless specified otherwise in a particular problem. For instance, t^6 can be expressed as (t^2)^3, which simplifies to x^3. However, it's important to note that taking the square root of both sides results in |t| = √x, indicating that t can be either √x or -√x. The discussion highlights the flexibility of variable substitution in algebraic expressions.