问题
解答题
一元二次方程一般形式:ax2+bx+c=0,(a≠0)两根记为x1,x2满足x1+x2=-
①x1+x1x2+x2 ②
③3x12-3x1+x22. |
答案
∵x1、x2是方程2x2-3x-1=0的两个实数根,
∴x1+x2=
,x1x2=-3 2
,2x12-3x1=1,1 2
①x1+x1x2+x2=(x1+x2)+x1x2=
-3 2
=1;1 2
②
+1 x1
=1 x2
=x1+x2 x1x2
=-3;3 2 - 1 2
③3x12-3x1+x22=2x12-3x1+x12+x22=1+(x1+x2)2-2x1x2=1+
-(-1)=49 4
.1 4