Question

求助：初二下数学题1、x^2-3x+1=0.则x^2+1/x^2= ? x-1/x=?2、若x+1/x=3,则分式想x^

Answer 1

1、X+1/X=3;可得X^2+1/X^2=(X+1/X)^2-2=7=(X-1/X)^2+2

X-1/X=正负根号5

2、分式=1/(X^2+1+X^-2);和第一题一个理,得1/8

3、C

4、-2