已知x2-1=4x,求x4次方+1/x4次方的值

问题描述:

已知x2-1=4x,求x4次方+1/x4次方的值

x²-1=4x
x-1/x=4
(x-1/x)²=16
x²+1/x²=18
x^4+1/x^4
=(x²+1/x²)²-2
=18²-2
=322