Given that the eqt x^2 + kx - (k-3) = 0 has real roots A and B.
If |A|=|B|,find thevalues of k.
A-MATHS
2007-07-03 5:34 am
回答 (1)
2007-07-03 2:08 pm
✔ 最佳答案
Given that the equation x^2 + kx - (k-3) = 0 has real roots A and B.If |A|=|B|,find thevalues of k.
First
A+B=-k...(1)
AB=3-k ...(2)
From (1)
B=A-k
|B|=|A-k|
Since |A|=|B|, combine
|A|= |A-k|
A= A-k or A= -(A-k)
k=0 or k=2A
when k=2A, B=-A
Since A+B=-k so k=0 again
the value of k is 0
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