Quantitative | Re: Tips and Tricks for Sequences Questions

Guys, lets start with few basic rules.

Rule 1: Positions in an AP or GP are relative to eachother.

Example: Given\(T_2\)=p,\(T_4\) =q find\(T_8\) , where\(T_n\) is the n-th term in the AP.

Think of\(T_4\)−\(T_2\) =q−p as one"step".
\(T_8\) is 2 steps away from\(T_4\) (think\(T_2,T_4,T_6,T_8\) ).
Hence\(T_8\) =q+2(q−p)=3q−2p

In this way we avoid having to first work out a and d by solving simultaneous equations and then applying the formula for\(T_8\) .

Rule 2: We can apply the concept of a zero or negative number-of-term