(1)
∵x+1/x=3
x²+1=3x
∴x²-3x=-1
(2)
∵x+1/x=3
(x+1/x)²=3²
∴x²+1/x²=7
∵(x²+1+x^4)/x²
=1+(1/x²)+x²
=1+7
=8
∴x²/(x²+1+x的4次方)=1/8