解:(1)1/(X1²)+1/蠢谈(X2²)=(X1²+X2²)/X1²X2=[(x1+x2)²-2x1x2]/(x1x2)²
=-1/25
(2))|X1-X2|=根号[(x1+x2)^2-4x1x2]=(带入就行,你给的两根如饥之和与积大小有问题)
(3)[(X2/渣档返X1)+1]+[(X1/X2)+1]
= X2/X1+X1/X2+2
=(x1+x2)^2/x1x2
(1)原式空启闷=(X1²+X2²)/(x1x2)²=[(x1+x2)²-2x1x2]/(x1x2)²旁茄=(9-10)/25=-1/斗弯25
(2)原式=√(x1+x2)²-4x1x2=√11i
(3)原式=(x1²+x2²)/(x1x1)+2=9/5