http://x85.xanga.com/29ac306553232152578852/b113890195.jpg
最尾果幅圖
The figure shows the graph of y = x 2次+ px +q which cuts the x-axis at A(1, 0)
and B(6,0).FIND
(a)the values of p and q.
(b)the optimum value of x2次 +px+q.
中4數學問題 有10點
2007-10-18 1:18 am
回答 (2)
2007-10-18 1:33 am
✔ 最佳答案
(a). A and B are the roots of the graph of y = x 2次+ px +q
(x-6)(x-1)=0
x^2-x-6x+6=0
x^2-7x+6=0
so p= -7 q=6
(b). x^2-7x+6
optimum value=4(1)(6)-(-7)^2 / 4(1) = -25/4
2007-10-17 17:33:18 補充：
俾10分我啦
參考: 自己
2007-10-18 1:35 am
a)
when x=1 , y=0
0= 1+q+p
p= -1-q -------(1)
when x=6 y=0
0=36+6p+q
6p+q=-36 ------ (2)
put (2) into (1)
6(-1-q)+q=-36
-6-6q+q=-36
-5q = -36+6
-5q = -30
q=6
put q= 6 into (1)
p = -1-6
p= -7
b)x*2+6x-7 =0
(x+7)(x-1)=0
x=-7 or x=1
when x=1 , y=0
0= 1+q+p
p= -1-q -------(1)
when x=6 y=0
0=36+6p+q
6p+q=-36 ------ (2)
put (2) into (1)
6(-1-q)+q=-36
-6-6q+q=-36
-5q = -36+6
-5q = -30
q=6
put q= 6 into (1)
p = -1-6
p= -7
b)x*2+6x-7 =0
(x+7)(x-1)=0
x=-7 or x=1
收錄日期: 2021-04-13 19:48:25
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20071017000051KK01973