Sequences

Sequences

1. Arithmetic Sequences

   • Un=Un-1 + d D IS THE COMMON DIFFERENCE
   • The nth term of an arithmetic sequence = a+(n-1)d

2. Arithmetic Series

   • You add the terms together instead of having a common difference
   • Un=a+(n-1)d

3. Sum of the first n natural numbers S = 1/2 n(n+1)

4. Sum of the first n terms of an arithmetic series

   • 1/2 n (a + l) the sum of the first n terms of an arithmetic series of the first n terms with the first term a and the last term l .
     • Alternative formula for Sn is Sn = 1/2n[2a+(n-1)d]

5. SIGMA

   • Σ TOP NUMBER MEANS END AT THIS NUMBER
     • BOTTOM NUMBER IS a, the first number