题目内容
先化简,再求值:
÷(
-4),其中x=
.
x2-4 |
x2+2x |
x2+4 |
x |
5 |
原式=
÷(
-
)
=
÷
=
÷
=
•
=
,
当x=
时,原式=
=
+2.
(x-2)(x+2) |
x(x+2) |
x2+4 |
x |
4x |
x |
=
(x-2)(x+2) |
x(x+2) |
x2-4x+4 |
x |
=
(x-2)(x+2) |
x(x+2) |
(x-2)2 |
x |
=
(x-2)(x+2) |
x(x+2) |
x |
(x-2)2 |
=
1 |
x-2 |
当x=
5 |
1 | ||
|
5 |
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