更新1:
Solve 5(2y-3)^2+14(2y-3)-3＜0
Maths
2010-11-24 1:33 am
David rides a bicycle from A to B on a straight path at a speech of (t+400)m/min.Paul rides another bicycle from B to A on the same straight path at a speed of( t+300)m/min .They start at the same time and meet each other after t minutes.It is known that the distance between A and B is between 7.2 km and 8 km inclusive .Find the range of possible values of t,corr to 1 decimal place.
回答 (2)
2010-11-24 8:15 am
✔ 最佳答案
----------------------------------------------------------------------------------------------------------圖片參考：http://img146.imageshack.us/img146/3795/inequalities1.png
2010-11-24 00:21:11 補充：
http://img146.imageshack.us/img146/3795/inequalities1.png
2010-11-27 23:07:52 補充：
第1 題, 有一個簡單d 的做法
由 7200 <=2 t^2 +700t <= 8000
3600 <= t^2+350t <= 4000
3600+ 175^2 <= t^2 +350t +175^2 <= 4000 + 175^2
34225 <= (t+175)^2 <= 34625
185 <= t+175 <= 186.08
10<= t <= 11.08
10 <=t <= 11
2010-11-24 2:14 am
t(400+t)+t(t+300)<7.2
t(400+t)+t(t+300)<8
I am a Form 3 student,I do not know how to solve it.
I hope it is correct!
t(400+t)+t(t+300)<8
I am a Form 3 student,I do not know how to solve it.
I hope it is correct!
收錄日期: 2021-04-24 09:44:31
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20101123000051KK00813