數學難題 (超急)(15分)

2007-10-26 5:10 pm

1. A manufacturer of lighting fixtures has daily production costs modeled by
y = 0.25x^2 - 10x + 800

where y is the total cost in dollars and x is the number of fixtures produced.

a. Sketch the graph of the model. Label the vertex.
b. What is the minimum daily production cost, y?
c. How many fixtures should be produced each day to yield a minimum cost?

更新1:

仲有一條，我其實都識識地的，不過計到出來唔知岩唔岩，所以想再問下 Figure: http://img.photobucket.com/albums/v439/pd3333/ADVBP%20Photo/tri.jpg a. Find x b. Find the sum of 3x and 4x c. Find difference between 3x+4x and 35

回答 (4)

雞尾包

2007-10-26 5:43 pm

✔ 最佳答案

y = 0.25x^2 - 10x + 800
= 0.25(x^2 - 40x) + 800
= 0.25(x^2 - 40x + 400) - 100 + 800
= 0.25(x - 20)^2 + 700
a. Sketch the graph of the model. Label the vertex.
vertex = (20, 700)
open upwards because a = 0.25 > 0
y - intercept = 800
you can plot it easily from this three conditions
-------------------------------------------------------------------
b. What is the minimum daily production cost, y?
minimum daily production cost = 700
-------------------------------------------------------------------
c. How many fixtures should be produced each day to yield a minimum cost?
no. of fixtures produced = 20

2007-10-26 09:44:24 補充：
上面位係咪做錯左??

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用戶7880

2007-10-27 2:27 am

Ans:20

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用戶105088

2007-10-26 6:50 pm

我用excel 做左, 依家send比你

2007-10-27 09:33:19 補充：
用左yahoo mail比你

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Ed Wong

2007-10-26 5:20 pm

a. vertex = 20
b. when x=0 => y=800
c. average cost per unit = y/x => At x = 56, min cost ~ 18.29

2007-10-26 09:26:32 補充：
Can use Gnuplot for (a)http://www.gnuplot.info/

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