a-1 |
b-2 |
1 |
ab |
1 |
(a+1)(b+1) |
1 |
(a+2)(b+2) |
1 |
(a+2011)(b+2001) |
|
|
1 |
2 |
1 |
2×3 |
1 |
3×4 |
1 |
2012×2013 |
1 |
2 |
1 |
2 |
1 |
3 |
1 |
3 |
1 |
4 |
1 |
2012 |
1 |
2013 |
1 |
2013 |
2012 |
2013 |
1 |
n(n+1) |
1 |
n |
1 |
n+1 |
非负数的性质:算术平方根.
本题考查了非负数的性质:几个非负数的和为0时,这几个非负数都为0,正确理解
=1 n(n+1)
-1 n
是关键.1 n+1
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