Chứng minh rằng (Un) là cấp số cộng khi và chỉ khi u=an+b

Look at the following graph of the given equation. determine whether the equation is a function. explain why or why not.

Which of the following represents a number squared is equal to twenty more than nine times that number ? a) x squared = 9x + 20 b) x squared = 20x + 9 c) x squared > 9 + 20x d) x squared = 9 + x + 20

If x varies directly as y, and x = 7.5 when y = 10, find x when y = 4