from2 manths?
2016-06-15 6:56 am
X sold goods which cost$200 to Y at a gain of c per cent, Y sold them back to X at a loss of c per cent. As a result Y lost $10.5. find c. ( I want the step, thanks)
回答 (1)
2016-06-15 9:26 am
The cost of Y to buy the goods
= The price that X sold the goods to Y
= $200 * (1 + c%)
When Y sold back the goods to X, the loss (in $) :
200 * (1 + c%) * c% = 10.5
2c (1 + 0.01c) = 10.5
0.02c² + 2c - 10.5 = 0
2c² + 200 - 1050 = 0
c² + 100c - 525 = 0
(c - 5)(c + 105) = 0
c - 5 = 0 or c + 105 = 0
c = 5 or c = -105 (rejected)
Hence, c = 5
= The price that X sold the goods to Y
= $200 * (1 + c%)
When Y sold back the goods to X, the loss (in $) :
200 * (1 + c%) * c% = 10.5
2c (1 + 0.01c) = 10.5
0.02c² + 2c - 10.5 = 0
2c² + 200 - 1050 = 0
c² + 100c - 525 = 0
(c - 5)(c + 105) = 0
c - 5 = 0 or c + 105 = 0
c = 5 or c = -105 (rejected)
Hence, c = 5
收錄日期: 2021-04-18 15:04:30
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20160614225637AAQ6agY