If the sum of a number and its square is 20, what is the number?  Choose the correct choice from the following answers.
A) 15  B) 26  C) 28  D) 4  E) none of these

Rationale: "let the number be x . then , x + x 2 = 20 ( x + 5 ) ( x - 4 ) = 0 x = 4 answer : d"
Answer: D