题目内容
计算:
(1)2-5+(
)-4+2-1×2-3×2+20
(2)
÷(
)2•
(3)
+
+
+…+
.
(1)2-5+(
| 1 |
| 2 |
(2)
| x2-6x+9 |
| x2-9 |
| x-3 |
| x+3 |
| 3 |
| 2x2+6x |
(3)
| 1 |
| x(x+1) |
| 1 |
| (x+1)(x+2) |
| 1 |
| (x+2)(x+3) |
| 1 |
| (x+99)(x+100) |
考点:分式的混合运算,零指数幂,负整数指数幂
专题:
分析:(1)运用负整数指数幂的运算法则,化简、运算、求值即可解决问题.
(2)首先将分式的分子、分母因式分解,然后约分、化简、求值即可解决问题.
(3)首先裂项,如将
裂为
-
,依次相加即可解决问题.
(2)首先将分式的分子、分母因式分解,然后约分、化简、求值即可解决问题.
(3)首先裂项,如将
| 1 |
| (x+99)(x+100) |
| 1 |
| x+99 |
| 1 |
| x+100 |
解答:解:(1)原式
=
+16+
×
×2+1
=
+
+17
=17
.
(2)原式
=
×
×
=
.
(3)原式
=
-
+
-
+
-
+…+
-
=
-
=
.
=
| 1 |
| 32 |
| 1 |
| 2 |
| 1 |
| 8 |
=
| 1 |
| 32 |
| 4 |
| 32 |
=17
| 5 |
| 32 |
(2)原式
=
| (x-3)2 |
| (x+3)(x-3) |
| (x+3)2 |
| (x-3)2 |
| 3 |
| 2x(x+3) |
=
| 3 |
| 2x2-6x |
(3)原式
=
| 1 |
| x |
| 1 |
| x+1 |
| 1 |
| x+1 |
| 1 |
| x+2 |
| 1 |
| x+2 |
| 1 |
| x+3 |
| 1 |
| x+99 |
| 1 |
| x+100 |
=
| 1 |
| x |
| 1 |
| x+100 |
=
| 100 |
| x(x+100) |
点评:该题主要考查了分式的混合运算问题;解题的关键是灵活变形,正确化简,准确计算.
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