解答下列各题:(1)计算:12?1-3tan230°+2(sin45°?1)2(2)解方程:3x2-4x-1=0
解答下列各题:(1)计算:12?1-3tan230°+2(sin45°?1)2(2)解方程:3x2-4x-1=0....
解答下列各题:(1)计算:12?1-3tan230°+2(sin45°?1)2(2)解方程:3x2-4x-1=0.
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(1)原式=
+1-3×(
)2+2|
-1|
=
+1-1+2-
=2;
(2)△=(-4)2-4×3×(-1)=28,
x=
=
,
所以x1=
2 |
| ||
3 |
| ||
2 |
=
2 |
2 |
=2;
(2)△=(-4)2-4×3×(-1)=28,
x=
4±
| ||
2×3 |
2±
| ||
3 |
所以x1=
2+
|