觀(guān)察下列過(guò)程:
12+1=2-1(2+1)(2-1)=2-1(2)2-12=2-12-1=2-1;
13+2=3-2(3+2)(3-2)=3-2(3)2-(2)2=3-23-2=3-2.
(1)運(yùn)用上述方法,可知:
15+2=5-25-2;
25-3=5+35+3;
1n+1+n=n+1-nn+1-n;
(2)計(jì)算:
23+1+25+3+…+22n+1+2n-1(n為正整數(shù)).
1
2
+
1
=
2
-
1
(
2
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1
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(
2
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1
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=
2
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1
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2
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2
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1
2
=
2
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1
2
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1
=
2
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1
1
3
+
2
=
3
-
2
(
3
+
2
)
(
3
-
2
)
=
3
-
2
(
3
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2
-
(
2
)
2
=
3
-
2
3
-
2
=
3
-
2
1
5
+
2
5
5
2
5
-
3
5
3
5
3
1
n
+
1
+
n
n
+
1
n
n
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1
n
2
3
+
1
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2
5
+
3
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…
+
2
2
n
+
1
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2
n
-
1
【考點(diǎn)】二次根式的混合運(yùn)算;分母有理化.
【答案】-2;+;-
5
5
3
n
+
1
n
【解答】
【點(diǎn)評(píng)】
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發(fā)布:2024/10/17 14:0:2組卷:69引用:1難度:0.5
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