中4數學問題 有10點

(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

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