11×2+12×3+13×4+…+198×99=98999899

11×2+12×3+13×4+…+198×99=98999899.
2025-04-04 00:38:06
推荐回答(1个)
回答1:

1
1×2
+
1
2×3
+
1
3×4
+…+
1
98×99

=(
1
1
-
1
2
)+(
1
2
-
1
3
)+(
1
3
-
1
4
)+…+(
1
98
-
1
99
),
=1-
1
99

=
98
99

故答案为:
98
99