Math Problem Statement

find all solutions of the recurrence relation an=2an-1+2n 2

Solution

To find the solutions to the recurrence relation an=2an1+2n+2a_n = 2a_{n-1} + 2n + 2, we can use the method of solving non-homogeneous recurrence relations. Let’s go through the steps:

Step 1: Identify the Homogeneous Part

The homogeneous part of the recurrence relation is: anh=2an1ha_n^h = 2a_{n-1}^h This is a first-order linear recurrence relation with the solution of the form: anh=C2na_n^h = C \cdot 2^n where CC is a constant.

Step 2: Find a Particular Solution

Now we need a particular solution for the non-homogeneous equation: an=2an1+2n+2a_n = 2a_{n-1} + 2n + 2 The non-homogeneous part 2n+22n + 2 suggests a linear function as a particular solution. Let’s assume anp=An+Ba_n^p = An + B as our particular solution form, where AA and BB are constants to be determined.

Substitute anp=An+Ba_n^p = An + B into the recurrence relation: An+B=2(A(n1)+B)+2n+2An + B = 2(A(n-1) + B) + 2n + 2 Expanding and simplifying, An+B=2An2A+2B+2n+2An + B = 2An - 2A + 2B + 2n + 2 Now, equate the coefficients of nn and the constant terms on both sides:

  1. Coefficient of nn: A=2A+2A=2A=2A = 2A + 2 \Rightarrow -A = 2 \Rightarrow A = -2
  2. Constant term: ( B = -2A + 2B + 2 \Rightarrow B = -2(-2) + 2B + 2 \Rightarrow B = 4 + 2 - B \Rightarrow B

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Math Problem Analysis

Mathematical Concepts

Recurrence Relations
Non-homogeneous Recurrence Relations
Linear Algebra

Formulas

an = 2an-1 + 2n + 2
an^h = C * 2^n
an^p = An + B

Theorems

Method of Solving Non-homogeneous Recurrence Relations

Suitable Grade Level

College Level