In the midst of grading exams now. One problem consists of computing determinants and many students give the answer [tex] (1+a)^3 -3a -1 [/tex] without simplifying it to [tex] a^3+3a^2 [/tex]. I have this nagging suspicion that they are not really able to expand a simple cubic. I wonder if this batch are those who at Primary 5 and 6, had algebra stripped out of their syllabus and replaced with some ghastly model building or what-you-call-it process.
*nothing to do with proper sub-algebras.