Generalize Theorem 1.3.9 by proving that every rational solution of a polyno- mial equation x" + an-1a"-1 + + a1x + = 0, | with integer coefficients ak, is an integer solution.

Advanced Engineering Mathematics
10th Edition
ISBN:9780470458365
Author:Erwin Kreyszig
Publisher:Erwin Kreyszig
Chapter2: Second-order Linear Odes
Section: Chapter Questions
Problem 1RQ
icon
Related questions
Question
12. Generalize Theorem 1.3.9 by proving that every rational solution of a polyno-
mial equation
-1x"-1
+ «1x + a• = 0,
+...
with integer coefficients a k,
is an integer solution.
Transcribed Image Text:12. Generalize Theorem 1.3.9 by proving that every rational solution of a polyno- mial equation -1x"-1 + «1x + a• = 0, +... with integer coefficients a k, is an integer solution.
Theorem 1.3.9. If k is an integer and the equation x = k has a rational solution,
then that solution is actually an integer.
Proof. Suppose r is a ratiomal number such that r2 = k. Let r =
as a fraction in which n and m have no common factors. Then,
er expressed
2
n
k
and so n? = m²k.
m
This equationm implies that m divides n2. However, if m 7 1, then m can be
expressed as a product of primes, and each of these primes must also divide n2.
However, if a prime number divides n2, it must also divide n (Exercise 1.3.14).
Thus, each prime factor of m divides n. Since n and m have no common factors,
this is impossible. We conclude that m =
1 and, hence, that r = n is an integer.
Transcribed Image Text:Theorem 1.3.9. If k is an integer and the equation x = k has a rational solution, then that solution is actually an integer. Proof. Suppose r is a ratiomal number such that r2 = k. Let r = as a fraction in which n and m have no common factors. Then, er expressed 2 n k and so n? = m²k. m This equationm implies that m divides n2. However, if m 7 1, then m can be expressed as a product of primes, and each of these primes must also divide n2. However, if a prime number divides n2, it must also divide n (Exercise 1.3.14). Thus, each prime factor of m divides n. Since n and m have no common factors, this is impossible. We conclude that m = 1 and, hence, that r = n is an integer.
Expert Solution
trending now

Trending now

This is a popular solution!

steps

Step by step

Solved in 2 steps

Blurred answer
Similar questions
Recommended textbooks for you
Advanced Engineering Mathematics
Advanced Engineering Mathematics
Advanced Math
ISBN:
9780470458365
Author:
Erwin Kreyszig
Publisher:
Wiley, John & Sons, Incorporated
Numerical Methods for Engineers
Numerical Methods for Engineers
Advanced Math
ISBN:
9780073397924
Author:
Steven C. Chapra Dr., Raymond P. Canale
Publisher:
McGraw-Hill Education
Introductory Mathematics for Engineering Applicat…
Introductory Mathematics for Engineering Applicat…
Advanced Math
ISBN:
9781118141809
Author:
Nathan Klingbeil
Publisher:
WILEY
Mathematics For Machine Technology
Mathematics For Machine Technology
Advanced Math
ISBN:
9781337798310
Author:
Peterson, John.
Publisher:
Cengage Learning,
Basic Technical Mathematics
Basic Technical Mathematics
Advanced Math
ISBN:
9780134437705
Author:
Washington
Publisher:
PEARSON
Topology
Topology
Advanced Math
ISBN:
9780134689517
Author:
Munkres, James R.
Publisher:
Pearson,