题目内容
已知x2-3x+1=0,则x-
=______.
1 |
x |
已知等式变形得:x+
=3,
两边平方得:(x+
)2=x2+2+
=9,即x2+
=7,
则(x-
)2=(x+
)2-2=7-2=5,
则x-
=±
.
故答案为:±
.
1 |
x |
两边平方得:(x+
1 |
x |
1 |
x2 |
1 |
x2 |
则(x-
1 |
x |
1 |
x |
则x-
1 |
x |
5 |
故答案为:±
5 |
练习册系列答案
相关题目