amaths

use this-----> D= b^2 －4ac
D= 0^2 -4k(-2(k+2)+3(k+2))
=-4k(k+2)
=-4k^2 -8k =0

-4k(k+2)=0
k= -2, 0 <-----不能，因為不為零


我讀英文的，唔知有冇理解錯

kx^2-2(k+2)+3(k+2)=0
kx^2-2k-4+3k+6=0
kx^2+(k+2)=0
since the equation has equal roots....so the discriminant of equation = 0
-4k(k+2)=0
k=0 or k=-2

I hope i can help u.....

2007-12-16 18:27:32 補充：
k=0(rejected) putx=0 into the equation,k(0)^2-2(k+2)+3(k+2) not equal to 0so 0 should be rejected