Question

x+1/x=a then x4+1/x4=?

Answer 1

(x+1/x) =a

Square on both sides,

(x+1/x)²=a²

x²+1/x²+2=a²

x²+1/x²=a²-2

Again square on both sides,

(x²+1/x²)²=(a²-2)²

x⁴+1/x⁴+2=(a²-2)²

x⁴+1/x⁴=a⁴+4-4a-2

x⁴+1/x⁴=a⁴+4a+2

Answer 2

Answer:

First squaring

X2+1/x2=a2-2

Second squaring

(X2)2+1/(x2)2=(a2)2-(2)2

X4+1/x4=a4+4-4a2-2

X4+1/x4=a4+4a2+2