题目
Problem
3. The quadratic equation
2x2−5x+7=0
has roots α and β
Without solving the equation,
(a) write down the value of (α+β) and the value of αβ
(1)
(b) determine, giving each answer as a simplified fraction, the value of
(i) α2+β2
(ii) α3+β3
(4)
(c) find a quadratic equation that has roots
α+β21 and β+α21
giving your answer in the form px2+qx+r=0 where p, q and r are integers to be determined.
(4)
题目中文翻译
- 二次方程
2x2−5x+7=0
的根为 α 和 β。
不解方程,
(a) 写出 (α+β) 和 αβ 的值。
(b) 求下列各式的值(答案用最简分数表示):
(i) α2+β2
(ii) α3+β3
(c) 求一个二次方程,使其根为
α+β21 和 β+α21
答案写成 px2+qx+r=0 的形式,其中 p、q 和 r 是待定整数。
解答