What does the symbol for factorial function (n! ) mean?

When turned about its axis of rotation, which shape could have created this three-dimensional object?

Gabriel determined that his total cost would be represented by 2.5x + 2y – 2. his sister states that the expression should be x + x + 0.5x + y + y – 2. who is correct? explain.

If 5x - 2 = -12, then x = a) -50 b) -4.4 c) -2.8 d) -2