Answer:
4 m squared minus 20 m n + 25 n squared; a perfect square trinomial
Explanation:
Given expression,
(negative 2 m + 5 n) squared

By using (a+b)² = a² + 2ab + b²,


∵ A trinomial which is the square of a binomial is called a perfect square trinomial.
Thus,
is a perfect square trinomial.