The square below has side 10x. find the area of the square remaining after a circle of radius 2x is removed from the square; in other words, find the area of the shaded region in factored form.

Suppose you are choosing a 6-digit personal access code. this code is made up of 4 digits chosen from 1 to 9, followed by 2 letters chosen from a to z. any of these digits or letters can be repeated. find the total number of personal access codes that can be formed. 492,804 341,172 39,917,124 4,435,236