1.观察下面的算式:6☆2=6+7=13 2☆3=2+3+4=9 5☆4=5+6+7+8=26 根据上面式子所表示的运算,求7☆5.2.(1+1/2)×(1-1/2)×(1+1/3)×(1-1/3)×……×(1+1/99)×(1-1/99)
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![1.观察下面的算式:6☆2=6+7=13 2☆3=2+3+4=9 5☆4=5+6+7+8=26 根据上面式子所表示的运算,求7☆5.2.(1+1/2)×(1-1/2)×(1+1/3)×(1-1/3)×……×(1+1/99)×(1-1/99)](/uploads/image/z/9314901-45-1.jpg?t=1.%E8%A7%82%E5%AF%9F%E4%B8%8B%E9%9D%A2%E7%9A%84%E7%AE%97%E5%BC%8F%3A6%E2%98%862%3D6%2B7%3D13+2%E2%98%863%3D2%2B3%2B4%3D9+5%E2%98%864%3D5%2B6%2B7%2B8%3D26+%E6%A0%B9%E6%8D%AE%E4%B8%8A%E9%9D%A2%E5%BC%8F%E5%AD%90%E6%89%80%E8%A1%A8%E7%A4%BA%E7%9A%84%E8%BF%90%E7%AE%97%2C%E6%B1%827%E2%98%865.2.%EF%BC%881%2B1%2F2%EF%BC%89%C3%97%EF%BC%881-1%2F2%EF%BC%89%C3%97%EF%BC%881%2B1%2F3%EF%BC%89%C3%97%EF%BC%881-1%2F3%EF%BC%89%C3%97%E2%80%A6%E2%80%A6%C3%97%EF%BC%881%2B1%2F99%EF%BC%89%C3%97%EF%BC%881-1%2F99%EF%BC%89)
1.观察下面的算式:6☆2=6+7=13 2☆3=2+3+4=9 5☆4=5+6+7+8=26 根据上面式子所表示的运算,求7☆5.2.(1+1/2)×(1-1/2)×(1+1/3)×(1-1/3)×……×(1+1/99)×(1-1/99)
1.观察下面的算式:6☆2=6+7=13 2☆3=2+3+4=9 5☆4=5+6+7+8=26 根据上面式子所表示的运算,求7☆5.
2.(1+1/2)×(1-1/2)×(1+1/3)×(1-1/3)×……×(1+1/99)×(1-1/99)
1.观察下面的算式:6☆2=6+7=13 2☆3=2+3+4=9 5☆4=5+6+7+8=26 根据上面式子所表示的运算,求7☆5.2.(1+1/2)×(1-1/2)×(1+1/3)×(1-1/3)×……×(1+1/99)×(1-1/99)
1) 7☆5=7+8+9+10+11=45
☆表示从7开始,连续加5个数.
2) (1+1/2)×(1-1/2)×(1+1/3)×(1-1/3)×……×(1+1/99)×(1-1/99)
=(3/2) × (1/2) × (4/3) × (2/3) × (5/4) × (3/4) ×.×(99/98) × (97/98) × (100/99) × (98/99)
=[(3/2) × (4/3) × (5/4) ×.×(99/98) × (100/99)]× [(1/2) × (2/3) × (3/4) ×.×(97/98) × (98/99)]
=[(1/2) × (1/1) × (1/1) ×.×(1/1) × (100/1)]× [(1/1) × (1/1) × (1/1) ×.×(1/1) × (1/99)]
=[100/2] × [1/99]
=50/99
把所有(1+1/n)的放一起,把所有(1-1/n)的放一起