The straight line y= 2x+k+2 touches the quadratic curve y= -x^2+6x-6 at one point. Find the value of k.
A-2 B.2 C.-4 D.4
problem on quadratic curve
2012-06-09 7:19 am
回答 (2)
2012-06-09 7:46 am
✔ 最佳答案
Equating the y's together:2x + k + 2 = -x^2 + 6x - 6
x^2 - 4x + (k + 8) = 0
Since they intersect at 1 point, discriminant of this equation is zero, i.e.
(-4)^2 - 4(k + 8) = 0
16 - 4(k + 8) = 0
k + 8 = 4
k = -4
Ans: C
參考: 原創答案
2012-06-09 8:10 am
It seems that the value of k is C.-4
收錄日期: 2021-04-27 15:40:37
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20120608000051KK00648