已知方程x2-3x+1=0的两根是x1,x2;则:x12+x22=_,1/x1+1/x2=_.
问题描述:
已知方程x2-3x+1=0的两根是x1,x2;则:x12+x22=______,
+1 x1
=______. 1 x2
答
由题意知,x1+x2=−
=3,x1x2=b a
=1,c a
x12+x22=(x1+x2)2-2x1x2=9-2=7,
+1 x1
=1 x2
=3,
x1+x2
x1x2
故填7;3.