What is the range of the quadratic function f(x) = x²?

The range of the quadratic function f(x) = x² is determined by the values that the function can take as x varies over all real numbers. Since this function is a parabola that opens upwards, the minimum value occurs at the vertex, which is at (0,0) for the function f(x) = x².

As x takes on any real number, the output f(x) will either be zero when x is zero or will be positive as x moves away in either direction (positive or negative). Therefore, the function produces values starting from zero and extending to positive infinity.

Thus, the range of f(x) = x² is [0, ∞), representing all real numbers that are greater than or equal to zero. This means that the function can achieve every value from zero upwards, which directly corresponds to the provided answer.