题目内容
若
=
=
，则
=
．
| x |
| 10 |
| y |
| 8 |
| z |
| 9 |
| x+y+z |
| y+z |
| 27 |
| 17 |
| 27 |
| 17 |
分析：可设
=
=
=k，则x=10k，y=8k，z=9k，再把x，y，z的值代入计算即可．
| x |
| 10 |
| y |
| 8 |
| z |
| 9 |
解答：解：设
=
=
=k，则x=10k，y=8k，z=9k，
∴
=
，
=
，
=
，
故答案为：
．
| x |
| 10 |
| y |
| 8 |
| z |
| 9 |
∴
| x+y+z |
| y+z |
| 10k+8k+9k |
| 8k+9k |
=
| 27k |
| 17k |
=
| 27 |
| 17 |
故答案为：
| 27 |
| 17 |
点评：本题考查了比例的基本性质，常用的性质有：①内项之积等于外项之积．若
=
，则ad=bc． ②合比性质．若
=
，则
=
．③分比性质．．若
=
，则
=
． ④合分比性质．．若
=
，则
=
．⑤等比性质．．若
=
=…=
（b+d+…+n≠0），则
=
．
| a |
| b |
| c |
| d |
| a |
| b |
| c |
| d |
| a+b |
| b |
| c+d |
| d |
| a |
| b |
| c |
| d |
| a-b |
| b |
| c-d |
| d |
| a |
| b |
| c |
| d |
| a+b |
| a-b |
| c+d |
| c-d |
| a |
| b |
| c |
| d |
| m |
| n |
| a+c+…+m |
| b+d+…+n |
| m |
| n |
练习册系列答案
相关题目