If x^2 + 1/x^2 = 2,what is the value of x^4 + 1/x^4 ?  Pick.
A) 10 B) 2 C) 4 D) 16 E) 18

Rationale: important : i notice that if we square x ² , we get x ⁴ , and if we square 1 / x ² , we get 1 / x ⁴ , so let ' s see what happens if we take the equation x ² + 1 / x ² = 2 andsquareboth sides : ( x ² + 1 / x ² ) ² = 4 so , ( x ² + 1 / x ² ) ( x ² + 1 / x ² ) = 4 expand to get : x ⁴ + 1 + 1 + 1 / x ⁴ = 4 simplify : x ⁴ + 1 / x ⁴ = 2 answer : b
Answer: B