题目内容
计算和解方程:
①(5
+2
)2-(
+5
)×
;
②3(
-π)0-
+(-1)2011;
④x2+4x-2=0.
①(5
| 3 |
| 5 |
| 12 |
| 5 |
| 3 |
②3(
| 3 |
| ||||
|
④x2+4x-2=0.
(1)原式=75+20
+20-(
×
+5
×
)=75+20
+20-6-5
=89+15
;
(2)原式=3-
-1=3-
-1=3-2+
-1=
;
(3)x2+4x-2=0,
移项得:x2+4x=2,
配方得:x2+4x+4=6,即(x+2)2=6,
可得x+2=
或x+2=-
,
解得:x1=
-1,x2=-
-2.
| 15 |
| 12 |
| 3 |
| 5 |
| 3 |
| 15 |
| 15 |
| 15 |
(2)原式=3-
| ||||||||
|
10-5
| ||
| 5 |
| 3 |
| 3 |
(3)x2+4x-2=0,
移项得:x2+4x=2,
配方得:x2+4x+4=6,即(x+2)2=6,
可得x+2=
| 6 |
| 6 |
解得:x1=
| 6 |
| 6 |
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