It takes 4 hours for two pipes to simultaneously fill up a swimming pool. If one
pipe at a time is used to fill up the swimming pool, the larger pipe would take 6 hours less than thesmaller pipe. Find the time it would take thesmaller pipe to fill
up the swimming pool.
quadratic equation
2010-08-18 3:32 am
回答 (1)
2010-08-18 3:39 am
✔ 最佳答案
Let the smaller pipe takes x hours to fill up the pool,then the bigger takes x - 6 hours to fill up it ,
1/x + 1/(x-6) = 1/4
(x-6) + x = (1/4)x(x-6)
2x - 6 = (1/4)(x^2 - 6x)
8x - 24 = x^2 - 6x
x^2 - 14x + 24 = 0
(x - 2)(x - 12) = 0
x = 2(rejected since x less then 4) or x = 12
Answer : 12 hours
2010-08-17 19:41:43 補充：
x bigger then 4 sorry.
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