232 STEP 4. Review the Knowledge You Need to Score High
11.1 Riemann Sums and Definite Integrals
Main Concepts:Sigma Notation, Definition of a Riemann Sum, Definition of
a Definite Integral, and Properties of Definite IntegralsSigma Notation or Summation Notation
∑ni= 1a 1 +a 2 +a 3 +···+anwhereiis the index of summation,lis the lower limit, andnis the upper limit of summation.
(Note: The lower limit may be any non-negative integer≤n.)Examples
∑^7i= 5i^2 = 52 + 62 + 72∑^3k= 02 k=2(0)+2(1)+2(2)+2(3)∑^3i=− 1(2i+1)=− 1 + 1 + 3 + 5 + 7∑^4k= 1(−1)k(k)=− 1 + 2 − 3 + 4Summation Formulas
Ifnis a positive integer, then:1.
∑ni= 1a=an2.
∑ni= 1i=
n(n+1)
23.
∑ni= 1i^2 =n(n+1)(2n+1)
64.
∑ni= 1i^3 =
n^2 (n+1)^2
45.
∑ni= 1i^4 =
n(n+1)(6n^3 + 9 n^2 +n−1)
30