Loading [MathJax]/jax/output/CommonHTML/fonts/TeX/fontdata.js

User interface language: English | Español

Date May 2014 Marks available 6 Reference code 14M.1.hl.TZ2.4
Level HL only Paper 1 Time zone TZ2
Command term Find Question number 4 Adapted from N/A

Question

The roots of a quadratic equation 2x2+4x1=0 are α and β.

Without solving the equation,

(a)     find the value of α2+β2;

(b)     find a quadratic equation with roots α2 and β2.

Markscheme

(a) using the formulae for the sum and product of roots:

α+β=2     A1

αβ=12     A1

α2+β2=(α+β)22αβ     M1

=(2)22(12)

=5     A1

 

Note:     Award M0 for attempt to solve quadratic equation.

 

[4 marks]

 

(b)     (xα2)(xβ2)=x2(α2+β2)x+α2β2     M1

x25x+(12)2=0     A1

x25x+14=0

 

Note:     Final answer must be an equation. Accept alternative correct forms.

 

[2 marks]

 

Total [6 marks]

Examiners report

[N/A]

Syllabus sections

Topic 2 - Core: Functions and equations » 2.6 » Sum and product of the roots of polynomial equations.

View options