If a2 - b2 = 5 and a*b = 2, find a4 + b4. Choose the correct choice.
A) 50  B) 72  C) 25  D) 92  E) 33

Rationale: "a 2 - b 2 = 5 : given a 4 + b 4 - 2 a 2 b 2 = 52 : square both sides and expand . a * b = 2 : given a 2 b 2 = 22 : square both sides . a 4 + b 4 - 2 ( 4 ) = 25 : substitute a 4 + b 4 = 33 correct answer e"
Answer: E