數學文字題
2007-01-07 10:43 pm
Mr. Tung deposited $10 000 in a banks on his 25th birthgay and $9000 on his 26th birthday.The interst was compounded yearly at r& p.a. , and the total amount he received on his 27th birthday was $22 000.Find r.
回答 (1)
2007-01-07 11:24 pm
✔ 最佳答案
We have10000*(1+r)^2+9000*(1+r)=22000
10000(1+2r+r^2)+9000(1+r)=22000
10000+20000r+10000r^2+9000+9000r=22000
10000r^2+29000r-3000=0
10r^2+29r-3=0
(10r-1)(r+3)=0
r=1/10 or r=-3 (rejected)
if the question is r% then
r=10
收錄日期: 2021-04-25 16:57:46
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20070107000051KK02399