If a and b are the two values of t that satisfy
the equation t^2 â€“ 12t + 20 = 0, with a > b, what is the value of a â€“ b?
Pick:
A) 2  B) 4  C) 6  D) 8  E) 10

Rationale: factor the left side of the equation : t ^ 2 â € “ 12 t + 20 = 0 ( t â € “ 2 ) ( t â € “ 10 ) = 0 t = 2 , t = 10 thus , a = 10 and b = 2 . so a â € “ b = 10 â € “ 2 = 8 . the answer is d .
Answer: D