SL Harder Sum of AP solutions
The most common errors on sums of sequences (and nth term) questions; in applied contexts, tend to be: (a) clarifying whether it is a sum of a sequence or an nth term question.(b) solving a quadratic (or other) equation quickly using the calculator (rather than rearranging and using the quadratic formula or completing the square/factorising etc.)/The full worked SOLUTIONS provide step-by-step guidance, for Casio and...