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(2013•黔西南州)(1)计算:(−1)2020×(12)−2+(sin98°−π2)0+|3−2sin60°|.(2)先化简,再求值:3x−3−18x2−9,其中x=10−3.
题目详情
(2013•黔西南州)(1)计算:(−1)2020×(
)−2+(sin98°−
)0+|
−2sin60°|.
(2)先化简,再求值:
−
,其中x=
−3.
1 |
2 |
π |
2 |
3 |
(2)先化简,再求值:
3 |
x−3 |
18 |
x2−9 |
10 |
▼优质解答
答案和解析
(1)原式=1×4+1+|
-2×
|
=4+1+|
-
|,
=4+1+0,
=5;
(2)原式=
=
=
=
.
当x=
-3时,原式=
=
3 |
| ||
2 |
=4+1+|
3 |
3 |
=4+1+0,
=5;
(2)原式=
3(x+3)−18 |
(x+3)(x−3) |
=
3x+9−18 |
(x+3)(x−3) |
=
3x−9 |
(x+3)(x−3) |
=
3 |
x+3 |
当x=
10 |
3 | ||
|
3
|
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