Maths Sequences Equations

Increasing Sequence

U[n-1]-U[n]>0 then U[n+1]>U[n]

Decreasing Sequence

U[n+1]-U[n]<0 then U[n+1]<U[n]

nth term arithmetic 

a+(n+1)d

nth term geometric 

ar^n-1

Sum of an infinite geometric sequence

a/1-r

Sum of an arithmetic sequence

n/2 [2a+(n+1)d] or n/2 (a+L)

Sum of a geometric sequence

[a(1-r^n)]/1-r