1.答案是857/512
思路是把它凑成等比数列,然后用求和公式求解,然后再化简.
2.原式=1-(1/12)+1-(1/24)+1-(1/48)+1-(1/96)+1-(1/192)+1-(1/384)
=6--(1/12)-(1/24)-(1/48)-(1/96)-(1/192)-(1/384)
=6-63/384(等比数列求和公式)
=2241/384
1.答案是857/512
思路是把它凑成等比数列,然后用求和公式求解,然后再化简.
2.原式=1-(1/12)+1-(1/24)+1-(1/48)+1-(1/96)+1-(1/192)+1-(1/384)
=6--(1/12)-(1/24)-(1/48)-(1/96)-(1/192)-(1/384)
=6-63/384(等比数列求和公式)
=2241/384