In a class of 5 , there are 3 students who have done their homework. If the teacher 2 chooses 2 2 students, what is the probability that none of them have done their homework?

Find the missing dimension! need asap! tiny square is a =3025 in ²

Set $r$ is a set of rectangles such that (1) only the grid points shown here are used as vertices, (2) all sides are vertical or horizontal and (3) no two rectangles in the set are congruent. if $r$ contains the maximum possible number of rectangles given these conditions, what fraction of the rectangles in set $r$ are squares? express your answer as a common fraction.

Which of the following constants can be added to x2 - 3x to form a perfect square trinomial?