OCR FP3 2015 June — Question 2

Exam BoardOCR
ModuleFP3 (Further Pure Mathematics 3)
Year2015
SessionJune
TopicGroups

2 The elements of a group \(G\) are polynomials of the form \(a + b x + c x ^ { 2 }\), where \(a , b , c \in \{ 0,1,2,3,4 \}\). The group operation is addition, where the coefficients are added modulo 5 .
  1. State the identity element.
  2. State the inverse of \(3 + 2 x + x ^ { 2 }\).
  3. State the order of \(G\). The proper subgroup \(H\) contains \(2 + x\) and \(1 + x\).
  4. Find the order of \(H\), justifying your answer.