先化简后求值x2?xx2?1?x2+xx2+2x+1÷x,其中x=2+1
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原式=
-
?
=
-
=
,
当x=
+1时,
原式=
=
=
x(x?1) |
(x+1)(x?1) |
x(x+1) |
(x+1)2 |
1 |
x |
=
x |
x+1 |
1 |
x+1 |
=
x?1 |
x+1 |
当x=
2 |
原式=
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=
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=
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