观察下列成立的式子:11×2=1-12,12×3=12-13,13×4=13-14,14×5=14-15…(1)则第n个算式为______=______.(2)如果将上列式子左右相加得:11×2+12×3+13×4+14×5=1-12+12-13+13-14+1-数学
1 |
n×(n+1) |
=1-
1 |
2 |
1 |
2 |
1 |
3 |
1 |
3 |
1 |
4 |
1 |
n |
1 |
n+1 |
=1-
1 |
n+1 |
=
n |
n+1 |
(3)
1 |
2 |
1 |
6 |
1 |
12 |
1 |
20 |
1 |
30 |
1 |
42 |
1 |
56 |
1 |
72 |
1 |
90 |
=
1 |
1×2 |
1 |
2×3 |
1 |
3×4 |
1 |
4×5 |
1 |
5×6 |
1 |
6×7 |
1 |
7×8 |
1 |
8×9 |
1 |
9×10 |
=1-
1 |
2 |
1 |
2 |