如X+1/X=3,X四次方+1/X四次方等于多少

问题描述:

如X+1/X=3,X四次方+1/X四次方等于多少

X4+1/X4
=(X²+1/X²)²-2
X²+1/X²=(X+1/X)²-2=7
则(X²+1/X²)²-2
=49-2
=47