Yahoo Answers: Answers and Comments for CE Maths [數學]
Copyright © Yahoo! Inc. All rights reserved.
https://answers.yahoo.com/question/index?qid=20090103000051KK01028
From Anonymous
enUS
Sat, 03 Jan 2009 15:12:22 +0000
3
Yahoo Answers: Answers and Comments for CE Maths [數學]
292
38
https://answers.yahoo.com/question/index?qid=20090103000051KK01028
https://s.yimg.com/zz/combo?images/emaillogous.png

From Kayla: by completing square,
f(x)
=x^2+bx+c
=(x+b/...
https://answers.yahoo.com/question/index?qid=20090103000051KK01028
https://answers.yahoo.com/question/index?qid=20090103000051KK01028
Sat, 03 Jan 2009 16:25:35 +0000
by completing square,
f(x)
=x^2+bx+c
=(x+b/2)^2  (b^2) /4 + c
given the line x=1 is the axis of symmetry,
 b/2 = 1
b= 2 < ans of (a)
sub (2,0) into y=x^22x+c
c= 0 < ans of (b)
ycoordinate of the vertex of the graph:  (b^2) /4 + c
sub b=2 and c= 0,
therefore, ycoordinate of the vertex of the graph = 1 < ans of (c)
when the graph is reflected in the yaxis,
f'(x)=(x1)^2 1
enlarged 2 times of the resulting graph along the yaxis,
f''(x)
= 2f'(x)
=2(x1)^2 2
therefore,ycoordinate of the vertex of the final graph = 2 < ans of (d)
20090103 16:30:53 補充：
sorry, part (d) 正負號打錯... 但答案應該一樣...
when the graph is reflected in the yaxis,
f'(x)=(x＋1)^2 1
enlarged 2 times of the resulting graph along the yaxis,
f''(x)
= 2f'(x)
=2(x＋1)^2 2
therefore,ycoordinate of the vertex of the final graph = 2 < ans of (d)