∵y1,y2是方程y^2-4y+1=0的两个根
∴y1+y2=4;y1*y2=1
y1^2+y2^2=(y1+y2)²-2y1y2=4²-2=14
1/y1+1/y2=(y1+y2)/y1y2=4
∵(y1-y2)²=(y1+y2)²-4y1y2=12
∴y1-y2=±2√3
.
∵y1,y2是方程y^2-4y+1=0的两个根
∴y1+y2=4;y1*y2=1
y1^2+y2^2=(y1+y2)²-2y1y2=4²-2=14
1/y1+1/y2=(y1+y2)/y1y2=4
∵(y1-y2)²=(y1+y2)²-4y1y2=12
∴y1-y2=±2√3
.