Is this set open or closed? [0,∞] and how is an infinity closed?

The expression 6x2 gives the surface area of a cube, and the expression x3 gives the volume of a cube, where x is the length of one side of the cube. find the surface area and the volume of a cube with a side length of 6m

Two friends are reading books. jimmy reads a book with 21,356 words. his friend bob reads a book with one-and-a-half times as many words. which expression represents the number of words bob reads?

More than 450450 students traveled to a state park for a field trip. the school allowed 66 students to travel by car, and the rest traveled on 1111 buses, each of which held the same number of students. if there were ss students in each bus, which inequality best represents this situation?