Power Series and Taylor’s Series Dr. Kamlesh Jangid Department of HEAS (Mathematics) Rajasthan Technical University, Kota-324010, India E-mail:
[email protected] Dr. Kamlesh Jangid (RTU Kota) Series 1 / 19 Outline Outline 1 Introduction 2 Series 3 Convergence and Divergence of Series 4 Power Series 5 Taylor’s Series Dr. Kamlesh Jangid (RTU Kota) Series 2 / 19 Introduction Overview Everyone knows how to add two numbers together, or even several. But how do you add infinitely many numbers together ? In this lecture we answer this question, which is part of the theory of infinite sequences and series. An important application of this theory is a method for representing a known differentiable function f (x) as an infinite sum of powers of x, so it looks like a "polynomial with infinitely many terms." Dr. Kamlesh Jangid (RTU Kota) Series 3 / 19 Series Definition A sequence of real numbers is a function from the set N of natural numbers to the set R of real numbers. If f : N ! R is a sequence, and if an = f (n) for n 2 N, then we write the sequence f as fang. A sequence of real numbers is also called a real sequence. Example (i) fang with an = 1 for all n 2 N-a constant sequence. n−1 1 2 (ii) fang = f n g = f0; 2 ; 3 ; · · · g; n+1 1 1 1 (iii) fang = f(−1) n g = f1; − 2 ; 3 ; · · · g. Dr. Kamlesh Jangid (RTU Kota) Series 4 / 19 Series Definition A series of real numbers is an expression of the form a1 + a2 + a3 + ··· ; 1 X or more compactly as an, where fang is a sequence of real n=1 numbers.