Help! Solutions/Quadratic Question (1 Viewer)

[tonyharrison]

From the 2006 HSC Maths Paper: Question 7 (a) (ii)
http://www.boardofstudies.nsw.edu.au/hsc_exams/hsc2006exams/pdf_doc/maths_06.pdf

Let A and B be the solutions of x^2 - 3x +1 = 0

(i) Find AB - simple
(ii) Hence find A + 1/A

Help?!

 

[anom1ly]

From the 2006 HSC Maths Paper: Question 7 (a) (ii)
http://www.boardofstudies.nsw.edu.au/hsc_exams/hsc2006exams/pdf_doc/maths_06.pdf

Let A and B be the solutions of x^2 - 3x +1 = 0

(i) Find AB - simple
(ii) Hence find A + 1/A

Help?!

AB = c/a = 1. Then, A = 1/B. So then A + 1/A = A + B.

 

[Bdogz]

AB=c/a=1 Therefore B=1/A A+B=-b/a=3 Substitute B=1/A A+1/A=3

 

[tonyharrison]

Thanks guys!