∵a=2，b=-4，c=-5
∴x=
−b±
| ||
| 2a |
4±
| ||
| 4 |
2±
| ||
| 2 |
x1=
2+
| ||
| 2 |
2−
| ||
| 2 |
2x2-4x-5=0．
2x2-4x-5=0．
数学人气：333 ℃时间：2020-03-30 00:25:42
优质解答
2x2-4x-5=0
∵a=2，b=-4，c=-5
∴x=
=
=
，
x1=
，x2=
．
∵a=2，b=-4，c=-5
∴x=
x1=
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