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IAL 2021 Oct FP1 Q3

A Level / Edexcel / FP1

IAL 2021 Oct Paper · Question 3

题目

Problem

3. The quadratic equation

2x25x+7=02x^2 - 5x + 7 = 0

has roots α\alpha and β\beta

Without solving the equation,

(a) write down the value of (α+β)(\alpha + \beta) and the value of αβ\alpha\beta

(1)

(b) determine, giving each answer as a simplified fraction, the value of

(i) α2+β2\alpha^2 + \beta^2

(ii) α3+β3\alpha^3 + \beta^3

(4)

(c) find a quadratic equation that has roots

1α+β2 and 1β+α2\dfrac{1}{\alpha + \beta^2} \text{ and } \dfrac{1}{\beta + \alpha^2}

giving your answer in the form px2+qx+r=0px^2 + qx + r = 0 where pp, qq and rr are integers to be determined.

(4)
题目中文翻译
  1. 二次方程

2x25x+7=02x^2 - 5x + 7 = 0

的根为 α\alphaβ\beta

不解方程,

(a) 写出 (α+β)(\alpha + \beta)αβ\alpha\beta 的值。

(b) 求下列各式的值(答案用最简分数表示):

(i) α2+β2\alpha^2 + \beta^2

(ii) α3+β3\alpha^3 + \beta^3

(c) 求一个二次方程,使其根为

1α+β2 和 1β+α2\dfrac{1}{\alpha + \beta^2} \text{ 和 } \dfrac{1}{\beta + \alpha^2}

答案写成 px2+qx+r=0px^2 + qx + r = 0 的形式,其中 ppqqrr 是待定整数。

解答