(a)
Write down a quadratic equation in x with roots 1 and -2.
(b)
The graph of the function y = k(k+α)(x-β) cuts the x-axis at A(1,0) and B(-2,0), and its y-intercept is -4 where k, α and β are positive constants. From the result of (a), find the values of α,β and k.
f.4 quadratic functions---
2009-11-02 8:01 am
回答 (1)
2009-11-02 8:08 am
✔ 最佳答案
(a) Sum of roots = - 1Product of roots = - 2
Equation: x2 + x - 2 = 0
(b) After expanding, the equation should be of the form:
y = k(x2 + x - 2)
since the equation y = 0 has x = 1 and -2 as roots.
Thus β = 1 and α = 2
Finally, - 2k is the y-intercept, giving k = 2
參考: Myself
收錄日期: 2021-04-13 16:55:17
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20091102000051KK00002