[H2_SAJC2006PromoQ1] Skipping Terms in an Arithmetic Progression

Question

Introduction

     This difficult-looking question has become pretty standard already.  There are some principles that the schools may or may not teach explicitly, but they expect students to know.  Let us review some of these principles.

Reminders

Refer also to this article.

Solution

Summary

     Remember that when you apply a formula (e.g. like the formula for the sum of an AP), you need to apply it with the appropriate numbers substituted.  Do not get stuck with the letters.  They are not meant to be taken literally, but change according to the situation.  For example, the “d” in the later part is  4  but it is different than the  d = 2  in the earlier part.

Heuristics Used

H04. Look for pattern(s)

H09. Restate the problem in another way

H10. Simplify the problem

H11. Solve part of the problem

H12* Think of a related problem

H13* Use Equation / write a Mathematical Sentence

Suitable Levels

* GCE ‘A’ Levels, H2 Mathematics 

* International Baccalaureate Mathematics 

* other syllabuses that involve arithmetic and geometric progressions