Log In Start studying!

Select your language

Suggested languages for you:
Answers without the blur. Sign up and see all textbooks for free! Illustration

Q52E

Expert-verified
Discrete Mathematics and its Applications
Found in: Page 527
Discrete Mathematics and its Applications

Discrete Mathematics and its Applications

Book edition 7th
Author(s) Kenneth H. Rosen
Pages 808 pages
ISBN 9780073383095

Answers without the blur.

Just sign up for free and you're in.

Illustration

Short Answer

Prove Theorem 6.

P(k) is true, for all positive integers k.

When s is not a root of the characteristic equation, then

ptnt+pt-1nt-1++p1n+p0sn is a particular solution.

When s is a root of the characteristic equation, then

nmptnt+pt-1nt-1++p1n+p0sn is a particular solution.

See the step by step solution

Step by Step Solution

Step 1: Previous Theorem

Theorem 1

The solution of the recurrence relation is of the form an=α1r1n+α2r2n when r1 and r2 the distinct roots of the characteristic equation.

Theorem 2

The solution of the recurrence relation is of the form r1,r2,,rk an=α1r1n+α2nr1n with r1 a root with multiplicity k of the characteristic equation.

Theorem 3

If a characteristic equation has the distinct roots r1,r2,,rk (each multiplicity l), then the recurrence relation has a solution of the form: an=α1r1n+α2r2n+.+αkrkn

Step 2: Use previous theorem 1

an satisfies the linear non homogeneous recurrence relation

an=c1an-1+c2an-2++ckan-k+F(n)

c1,c2,,ck are real numbers

F(n)=btnt+bt-1nt-1++b1n+b0sn

b0,b1,,bt,s are real numbers

To proof: When is not a root of the characteristic equation, then

ptnt+pt-1nt-1++p1n+p0sn is a particular solution.

When is a root of the characteristic equation, then

nmptnt+pt-1nt-1++p1n+p0sn is a particular solution.

Let P(t) be "When s is not a root of the characteristic equation, then

ptnt+pt-1nt-1++p1n+p0sn is a particular solution. When s is a root of the

characteristic equation, then nmptnt+pt-1nt-1++p1n+p0sn is a particular solution.

Step 3: Use previous theorem 2

Let t=0 and consider s is not a root, then:

c1an-1+c2an-2++ckan-k+F(n)=c1p0sn-1+c2p0sn-2+.+ckp0sn-k+b0snc1an-1+c2an-2++ckan-k+F(n)=p0an(h)+b0snc1an-1+c2an-2++ckan-k+F(n)=p0an(h)+F(n)

c1an-1+c2an-2++ckan-k+F(n)=an for some choice of is a root

c1an-1+c2an-2++ckan-k+F(n)=c1p0(n-1)msn-1+c2p0(n-2)msn-2+.+ckp0(n-k)msn-k+b0snc1an-1+c2an-2++ckan-k+F(n)=p0(n-1)(n-2)(n-k)an(h)+F(n)

c1an-1+c2an-2++ckan-k+F(n)=an for some choice of p-0

Thus P(0) is true.

Step 4: Use previous theorem 3

Let P(0),P(1),,P(k) be true.

When s is not a root of the characteristic equation, then

pknk+pk-1nk-1++p1n+p0sn is a particular solution. When s is a root of the characteristic equation, then nmpknk+pk-1nk-1++p1n+p0sn is a particular solution.

We need to proof thatP(k+1) is true and is not a rootc1an-1+c2an-2++ckan-k+F(n)=c1pk+1(n-1)k+1sn-1+c2pk+1(n-2)k+1sn-2+b0snc1an-1+c2an-2++ckan-k+F(n)=pk+1(n-1)k+1an(h)+b0snc1an-1+c2an-2++ckan-k+F(n)=pk+1(n-1)k+1+F(n)

c1an-1+c2an-2++ckan-k+F(n)=an for some choice of is a root.

c1an-1+c2an-2++ckan-k+F(n)=c1pk+1(n-1)k+1sn-1+c2pk+1(n-2)k+1sn-2+b0snc1an-1+c2an-2++ckan-k+F(n)=pk+1(n-1)k+1an(h)+b0snc1an-1+c2an-2++ckan-k+F(n)=pk+1(n-1)k+1+F(n)

c1an-1+c2an-2++ckan-k+F(n)=an for some choice of p-k+1

Thus pk+1nk+1sn is a particular solution when is not a root.

However, pknk+pk-1nk-1++p1n+p0sn is also a particular solution as P(k) is

true and thus pk+1nk+1sn+pknk+

pk-1nk-1++p1n+p0sn=pk+1nk+1+pknk+pk-1nk-1++p1n+p0snis also a particular solution.

Similarly, pk+1nmnk+1sn is a particular solution when s is not a root. However,

nmpknk+pk-1nk-1++p1n+p0sn is also a particular solution as P(k) is true and

thus pk+1nmnk+1sn+ nmpknk+pk-1nk-1++p1n+p0sn=nmpk+1nk+1+pknk+pk-1nk-1++p1n+p0snis also a particular solution.

Thus P(k+1) is true.

By the principal of mathematical induction: P(k) is true, for all positive integers k.

When s is not a root of the characteristic equation, then

ptnt+pt-1nt-1++p1n+p0sn is a particular solution.

When s is a root of the characteristic equation, then

nmptnt+pt-1nt-1++p1n+p0sn is a particular solution.

Recommended explanations on Math Textbooks

94% of StudySmarter users get better grades.

Sign up for free
94% of StudySmarter users get better grades.