OCR C2 2012 January — Question 5

Exam BoardOCR
ModuleC2 (Core Mathematics 2)
Year2012
SessionJanuary
TopicFactor & Remainder Theorem
TypeProve root count with given polynomial

5 The cubic polynomial \(\mathrm { f } ( x )\) is defined by \(\mathrm { f } ( x ) = 2 x ^ { 3 } + 3 x ^ { 2 } - 17 x + 6\).
  1. Find the remainder when \(\mathrm { f } ( x )\) is divided by \(( x - 3 )\).
  2. Given that \(\mathrm { f } ( 2 ) = 0\), express \(\mathrm { f } ( x )\) as the product of a linear factor and a quadratic factor.
  3. Determine the number of real roots of the equation \(\mathrm { f } ( x ) = 0\), giving a reason for your answer.