To find the quadratic function related to the square root function \( k(x) = 5\sqrt{x} \), we can rewrite the square root function in terms of a quadratic function.
Recall that the square root function can be expressed as follows:
\[ k(x) = 5\sqrt{x} \]
We can rewrite this in terms of a quadratic function by squaring both sides:
\[ k(x)^2 = (5\sqrt{x})^2 = 25x \]
This means that if \( m(x) \) is the corresponding quadratic function, we can express it as:
\[ m(x) = 25x \]
Since we are looking for a quadratic function \( m(x) \) that relates to the square root function \( k(x) \), we match it to the options provided. Notice that the form \( m(x) = 25x^2 \) corresponds to the representation of the quadratic function derived from the original square root function.
Thus, the correct answer is:
m(x) = 25x^2