Question 581926
*[tex \LARGE x^2 \ge 15x \Rightarrow x^2 - 15x \ge 0]


This factors


*[tex \LARGE x(x-15) \ge 0]


If x = 0 or x = 15, the inequality becomes an equality. It can easily be checked that all x >= 15 and x <= 0 satisfy the inequality.