A. maths
Modulus Function :
Sketch graph f(x)= | x^2 - 4x +3 | for the domain 0<x<5 and state the corresponding range of f(x).
Can someone tell me how to find the corresponding range of f(x) ??
the answer is 0<f(x)<8 ... Why?
Thank you
回答 (2)
First set x²-4x+3=0
(x-1)(x-3)=0
∴f(x)=0 when x=1 or 3, which is in the range of [0,5]
∴Min value of f(x)=0 as | x^2 - 4x +3 | must be greater than or =0
Consider tha shape of x²-4x+3, it is opening upward from the two sides, so it is obvious that the max. value occurs at the end pt.
f(0)=3
f(5)=8
∴Max. value of f(x)=8
∴range of f(x)=0 to 8
i can tell you how to find the corresponding range of f(x)
consider
g(x)=x^2 - 4x +3
=(x-3)(x-1)
when x=1 or 3
g(x)=0
Since the cofficient of the x^2 is 1 , the graph is upward
This means that g(0) or g(5) should be the largest one
Since g(5)=8>g(0)=3
And f(x)=|g(x)| should be >=0
so the corresponding range of f(x) is
0<=x<8
2008-06-07 21:20:41 補充:
> >
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2008-06-07 21:21:28 補充:
YAHOO時常想人手機認證
2008-06-07 21:46:28 補充:
because x=1 and x=3 is belonged to the domain 0<5
So the minmimum value of f(x) is 0
2008-06-07 21:48:00 補充:
AS YOU KNOW THAT
第一個人當然無表達得0甘好﹐因為無參考資料。
收錄日期: 2021-04-25 16:58:41
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