1. convert the decimals into fractions
0.17(有粒點係7既上面）
0.17(有2粒點分別係1同7既上面)
ps* 2題都係recurring decimal
仲有...呢類型題個concept係乜..=[
請列式..
F.4 maths....(10分)
2007-08-28 12:56 am
回答 (2)
2007-08-28 5:34 pm
✔ 最佳答案
計循環小數既時候我地第一步要做既係消除d循環小數,慣常既做法係"先乘後減".
Q.1
let x = 0.1777777777777777777777777777777777...
then 10x = 1.77777777777777777777777777777777...
10x - x
= 9x
= 1.77777777777777777777777...
-0.17777777777777777777777...
=1.6
9x = 1.6
x = 1.6/9 = 16/90 = 8/45
Q.2
let x = 0.17171717171717171717171717...
then 100x = 17.1717171717171717171717...
100x - x = 99x = 17
x = 17/99
參考: 我
2007-08-28 1:52 am
0.1(7)
= 0.1+ 0.0(7)
=1/10 + 7/90
=16/90
=8/45
0.(17)
=17/99
concept:
If the number is between 0.1~1 & the repeat block is n-digits long
then the fraction will be the repeat block over n-digits of 9.
{example is the second one which is 2-digit long & hence 17(repeat block)/99}
If the number is between 0~0.1 & have k-digits long of o before the repeat block of n-digit long, the fraction will be the block over the integer consist n-digit of 9 follow by k-digit of 0.
{example is 0.0(7), hence 1digit long of repeat block with 1digit of 0 in front. so it will be 7/90}
= 0.1+ 0.0(7)
=1/10 + 7/90
=16/90
=8/45
0.(17)
=17/99
concept:
If the number is between 0.1~1 & the repeat block is n-digits long
then the fraction will be the repeat block over n-digits of 9.
{example is the second one which is 2-digit long & hence 17(repeat block)/99}
If the number is between 0~0.1 & have k-digits long of o before the repeat block of n-digit long, the fraction will be the block over the integer consist n-digit of 9 follow by k-digit of 0.
{example is 0.0(7), hence 1digit long of repeat block with 1digit of 0 in front. so it will be 7/90}
收錄日期: 2021-04-13 20:01:30
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20070827000051KK03561