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Date May 2014 Marks available 6 Reference code 14M.1.hl.TZ1.4
Level HL only Paper 1 Time zone TZ1
Command term Find Question number 4 Adapted from N/A

Question

The equation \(5{x^3} + 48{x^2} + 100x + 2 = a\) has roots \({r_1}\), \({r_2}\) and \({r_3}\).

Given that \({r_1} + {r_2} + {r_3} + {r_1}{r_2}{r_3} = 0\), find the value of a.

Markscheme

\({r_1} + {r_2} + {r_3} = \frac{{ - 48}}{5}\)     (M1)(A1)

\({r_1}{r_2}{r_3} = \frac{{a - 2}}{5}\)     (M1)(A1)

\(\frac{{ - 48}}{5} + \frac{{a - 2}}{5} = 0\)     M1

\(a = 50\)     A1

 

Note:     Award M1A0M1A0M1A1 if answer of 50 is found using \(\frac{{48}}{5}\) and \(\frac{{2 - a}}{5}\).

 

[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.

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