问题
解答题
已知方程x2-3x-1=0的两根为x1、x2,求
|
答案
∵x1+x2=3,x1•x2=-1,
∴
+x2 x1
=x1 x2
=
+x 22 x 21 x1x2 (x1+x2)2-2x1x2 x1x2
=
=-1132-2×(-1) -1
已知方程x2-3x-1=0的两根为x1、x2,求
|
∵x1+x2=3,x1•x2=-1,
∴
+x2 x1
=x1 x2
=
+x 22 x 21 x1x2 (x1+x2)2-2x1x2 x1x2
=
=-1132-2×(-1) -1