(7/8+7/9+7/10+7/11)*(7/9+7/10+7/11+7/12)-(7/8+7/9+7/10+7/11+
来源:学生作业帮 编辑:搜搜考试网作业帮 分类:数学作业 时间:2024/08/05 05:47:52
(7/8+7/9+7/10+7/11)*(7/9+7/10+7/11+7/12)-(7/8+7/9+7/10+7/11+7/12)*(7/9+7/10+7/11)求帮助,谢谢!
![(7/8+7/9+7/10+7/11)*(7/9+7/10+7/11+7/12)-(7/8+7/9+7/10+7/11+](/uploads/image/z/17093595-3-5.jpg?t=%287%2F8%2B7%2F9%2B7%2F10%2B7%2F11%29%2A%287%2F9%2B7%2F10%2B7%2F11%2B7%2F12%29-%287%2F8%2B7%2F9%2B7%2F10%2B7%2F11%2B)
(7/8+7/9+7/10+7/11)*(7/9+7/10+7/11+7/12)-(7/8+7/9+7/10+7/11+7/12)*(7/9+7/10+7/11)
=(7/8+7/9+7/10+7/11)×(7/9+7/10+7/11+7/12)-(7/8+7/9+7/10+7/11)×(7/9+7/10+7/11)-7/12×(7/9+7/10+7/11)
=(7/8+7/9+7/10+7/11)×【(7/9+7/10+7/11+7/12)-(7/9+7/10+7/11)】-7/12×(7/9+7/10+7/11)
=(7/8+7/9+7/10+7/11)×【7/9+7/10+7/11+7/12-7/9-7/10-7/11】-7/12×(7/9+7/10+7/11)
=(7/8+7/9+7/10+7/11)×7/12-7/12×(7/9+7/10+7/11)
=(7/8+7/9+7/10+7/11-7/9-7/10-7/11)×7/12
=7/8×7/12
=49/96
=(7/8+7/9+7/10+7/11)×(7/9+7/10+7/11+7/12)-(7/8+7/9+7/10+7/11)×(7/9+7/10+7/11)-7/12×(7/9+7/10+7/11)
=(7/8+7/9+7/10+7/11)×【(7/9+7/10+7/11+7/12)-(7/9+7/10+7/11)】-7/12×(7/9+7/10+7/11)
=(7/8+7/9+7/10+7/11)×【7/9+7/10+7/11+7/12-7/9-7/10-7/11】-7/12×(7/9+7/10+7/11)
=(7/8+7/9+7/10+7/11)×7/12-7/12×(7/9+7/10+7/11)
=(7/8+7/9+7/10+7/11-7/9-7/10-7/11)×7/12
=7/8×7/12
=49/96