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Each of exercises 51-53 refers to the Euler phi function, denoted ϕ , which is defined as follows: For each integer n ≥ 1 , ϕ ( n ) is the number of positive integers less than or equal to n that have no common factors with n except ± 1 . For example, ϕ ( 10 ) = 4 because there are four positive integers less than or equal to 10 that have no common factor with 10 except ± 1 -namely, 1,3,7, and9. Prove that there are infinitely many integers n for which ϕ ( n ) is a perfect square.

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Discrete Mathematics With Applicat...

5th Edition
EPP + 1 other
Publisher: Cengage Learning,
ISBN: 9781337694193
BuyFind

Discrete Mathematics With Applicat...

5th Edition
EPP + 1 other
Publisher: Cengage Learning,
ISBN: 9781337694193

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Chapter
Section
Chapter 7.1, Problem 53ES
Textbook Problem

Each of exercises 51-53 refers to the Euler phi function, denoted ϕ , which is defined as follows: For each integer n 1 , ϕ ( n ) is the number of positive integers less than or equal to n that have no common factors with n except ± 1 . For example, ϕ ( 10 ) = 4 because there are four positive integers less than or equal to 10 that have no common factor with 10 except ± 1 -namely, 1,3,7, and9.

Prove that there are infinitely many integers n for which ϕ ( n ) is a perfect square.

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Chapter 7 Solutions

Discrete Mathematics With Applications
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Ch. 7.1 - Let X={1,3,5} and Y={a,b,c,d}. Define g:XY by the...Ch. 7.1 - Indicate whether the statement in parts (a)-(d)...Ch. 7.1 - a. Find all function from X={a,b}toY={u,v} . b....Ch. 7.1 - Let Iz be the identity function defined on the set...Ch. 7.1 - Find function defined on the sdet of nonnegative...Ch. 7.1 - Let A={1,2,3,4,5} , and define a function F:P(A)Z...Ch. 7.1 - Let Js={0,1,2,3,4} , and define a function F:JsJs...Ch. 7.1 - Define a function S:Z+Z+ as follows: For each...Ch. 7.1 - Let D be the set of all finite subsets of positive...Ch. 7.1 - Define F:ZZZZ as follows: For every ordered pair...Ch. 7.1 - Let JS={0,1,2,3,4} ,and define G:JsJsJsJs as...Ch. 7.1 - Let Js={0,1,2,3,4} , and define functions f:JsJs...Ch. 7.1 - Define functions H and K from R to R by the...Ch. 7.1 - Let F and G be functions from the set of all real...Ch. 7.1 - Let F and G be functions from the set of all real...Ch. 7.1 - Use the definition of logarthum to fill in the...Ch. 7.1 - Find exact values for each of the following...Ch. 7.1 - Use the definition of logarithm to prove that for...Ch. 7.1 - Use the definition of logarithm to prove that for...Ch. 7.1 - If b is any positive real number with b1 and x is...Ch. 7.1 - Use the unique factorizations for the integers...Ch. 7.1 - If b and y are positive real numbers such that...Ch. 7.1 - If b and y are positivereal numbers such that...Ch. 7.1 - Let A={2,3,5} and B={x,y}. Let p1 and p2 be the...Ch. 7.1 - Observe that mod and div can be defined as...Ch. 7.1 - Let S be the set of all strings of as and bs....Ch. 7.1 - Consider the coding and decoding functions E and D...Ch. 7.1 - Consider the Hamming distance function defined in...Ch. 7.1 - Draw arrow diagram for the Boolean functions...Ch. 7.1 - Fill in the following table to show the values of...Ch. 7.1 - Cosider the three-place Boolean function f defined...Ch. 7.1 - Student A tries to define a function g:QZ by the...Ch. 7.1 - Student C tries to define a function h:QQ by the...Ch. 7.1 - Let U={1,2,3,4} . Student A tries to define a...Ch. 7.1 - Let V={1,2,3} . Student C tries to define a...Ch. 7.1 - On certain computers the integer data type goed...Ch. 7.1 - Let X={a,b,c} and Y={r,s,tu,v,w} , Define f:XY as...Ch. 7.1 - Let X={1,2,3,4} and Y={a,b,c,e} . Define g:XY as...Ch. 7.1 - Let X and Y be sets, let A and B be any subsets of...Ch. 7.1 - In 41-49 let X and Y be sets, let A and B be any...Ch. 7.1 - In 41-49 let X and Y be sets, let A and B be any...Ch. 7.1 - In 41-49 let X and Y be sets, let A and B be any...Ch. 7.1 - In 41-49 let X and Y be sets, let A and B be any...Ch. 7.1 - In 41-49 let X and Y be sets, let A and B be any...Ch. 7.1 - In 41-49 let X and Y be sets, let A and B be any...Ch. 7.1 - In 41-49 let X and Y be sets, let A and B be any...Ch. 7.1 - In 41-49 let X and Y be sets, let A and B be any...Ch. 7.1 - In 41-49 let X and Y be sets, let A and B be any...Ch. 7.1 - Given a set S and a subset A, the characteristic...Ch. 7.1 - Each of exercises 51-53 refers to the Euler phi...Ch. 7.1 - Each of exercises 51-53 refers to the Euler phi...Ch. 7.1 - Each of exercises 51-53 refers to the Euler phi...Ch. 7.2 - If F is a function from a set X to a set Y, then F...Ch. 7.2 - If F is a function from a set X to a set Y, then F...Ch. 7.2 - If F is a function from a set X to a set Y, then F...Ch. 7.2 - If F is a function from a set X to a set Y, then F...Ch. 7.2 - The following two statements are_______....Ch. 7.2 - Given a function F:XY where X is an infinite set,...Ch. 7.2 - Given a function F:XY where X is an infinite set,...Ch. 7.2 - Given a function F:XY , to prove that F is not one...Ch. 7.2 - Given a function F:XY , to prove that F is not...Ch. 7.2 - A one-to-one correspondence from a set X to a set...Ch. 7.2 - If F is a one-to-one correspondence from a set X...Ch. 7.2 - The definition of onr-to-one is stated in two...Ch. 7.2 - Fill in each blank with the word most or least. a....Ch. 7.2 - When asked to state the definition of one-to-one,...Ch. 7.2 - Let f:XY be a function. True or false? A...Ch. 7.2 - All but two of the following statements are...Ch. 7.2 - Let X={1,5,9} and Y={3,4,7} . a. Define f:XY by...Ch. 7.2 - Let X={a,b,c,d} and Y={e,f,g} . Define functions F...Ch. 7.2 - Let X={a,b,c} and Y={d,e,f,g} . Define functions H...Ch. 7.2 - Let X={1,2,3},Y={1,2,3,4} , and Z= {1,2} Define a...Ch. 7.2 - a. Define f:ZZ by the rule f(n)=2n, for every...Ch. 7.2 - Define F:ZZZZ as follows. For every ordered pair...Ch. 7.2 - a. Define F:ZZ by the rule F(n)=23n for each...Ch. 7.2 - a. Define H:RR by the rule H(x)=x2 , for each real...Ch. 7.2 - Explain the mistake in the following “proof.”...Ch. 7.2 - In each of 15-18 a function f is defined on a set...Ch. 7.2 - In each of 15-18 a function f is defined on a set...Ch. 7.2 - In each of 15-18 a function f is defined on a set...Ch. 7.2 - In each of 15-18 a function f is defined on a set...Ch. 7.2 - Referring to Example 7.2.3, assume that records...Ch. 7.2 - Define Floor: RZ by the formula Floor (x)=x , for...Ch. 7.2 - Let S be the set of all string of 0’s and 1’s, and...Ch. 7.2 - Let S be the set of all strings of 0’s and 1’s,...Ch. 7.2 - Define F:P({a,b,c})Z as follaws: For every A in...Ch. 7.2 - Les S be the set of all strings of a’s and b’s,...Ch. 7.2 - Let S be the et of all strings is a’s and b’s, and...Ch. 7.2 - Define S:Z+Z+ by the rule: For each integer n,...Ch. 7.2 - Let D be the set of all set of all finite subsets...Ch. 7.2 - Define G:RRRR as follows:...Ch. 7.2 - Define H:RRRR as follows: H(x,y)=(x+1,2y) for...Ch. 7.2 - Define J=QQR by the rule J(r,s)=r+2s for each...Ch. 7.2 - De?ne F:Z+Z+Z+ and G:Z+Z+Z+ as follows: For each...Ch. 7.2 - a. Is log827=log23? Why or why not? b. Is...Ch. 7.2 - The properties of logarithm established in 33-35...Ch. 7.2 - The properties of logarithm established in 33-35...Ch. 7.2 - The properties of logarithm established in 33-35...Ch. 7.2 - Exercise 36 and 37 use the following definition:...Ch. 7.2 - Exercise 36 and 37 use the following definition:...Ch. 7.2 - Exercises 38 and 39 use the following definition:...Ch. 7.2 - Exercises 38 and 39 use the following definition:...Ch. 7.2 - Suppose F:XY is one—to—one. a. Prove that for...Ch. 7.2 - Suppose F:XY is into. Prove that for every subset...Ch. 7.2 - Let X={a,b,c,d,e}and Y={s,tu,v,w}. In each of 42...Ch. 7.2 - Let X={a,b,c,d,e}and Y={s,tu,v,w}. In each of 42...Ch. 7.2 - In 44-55 indicate which of the function in the...Ch. 7.2 - In 44-55 indicate which of the function in the...Ch. 7.2 - In 44-55 indicate which of the function in the...Ch. 7.2 - In 44-55 indicate which of the function in the...Ch. 7.2 - In 44-55 indicate which of the function in the...Ch. 7.2 - In 44-55 indicate which of the function in the...Ch. 7.2 - In 44-55 indicate which of the function in the...Ch. 7.2 - In 44-55 indicate which of the function in the...Ch. 7.2 - In 44-55 indicate which of the functions in the...Ch. 7.2 - In 44-55 indicate which of the functions in the...Ch. 7.2 - In 44-55 indicate which of the functions in the...Ch. 7.2 - In 44-55 indicate which of the functions in the...Ch. 7.2 - In Example 7.2.8 a one-to-one correspondence was...Ch. 7.2 - Write a computer algorithm to check whether a...Ch. 7.2 - Write a computer algorithm to check whether a...Ch. 7.3 - If f is a function from X to Y’,g is a function...Ch. 7.3 - If f is a function from X to Y and Ix and Iy are...Ch. 7.3 - If f is a one-to=-one correspondence from X to Y....Ch. 7.3 - If f is a one-to-one function from X to Y and g is...Ch. 7.3 - If f is an onto function from X to Y and g is an...Ch. 7.3 - In each of 1 and 2, functions f and g are defined...Ch. 7.3 - In each of 1 and 2, functions f and g are defined...Ch. 7.3 - In 3 and 4, functions F and G are defined by...Ch. 7.3 - In 3 and 4, functions F and G are defined by...Ch. 7.3 - Define f:RR by the rule f(x)=x for every real...Ch. 7.3 - Define F:ZZ and G:ZZ . By the rules F(a)=7a and...Ch. 7.3 - Define L:ZZ and M:ZZ by the rules L(a)=a2 and...Ch. 7.3 - Let S be the set of all strings in a’s and b’s and...Ch. 7.3 - Define F:RR and G:RZ by the following formulas:...Ch. 7.3 - Define F:ZZ and G:ZZ by the rules F(n)=2n and...Ch. 7.3 - Define F:RR and G:RR by the rules F(n)=3x and...Ch. 7.3 - The functions of each pair in 12—14 are inverse to...Ch. 7.3 - G:R+R+ and G1:RR+ are defined by G(x)=x2andG1(x)=x...Ch. 7.3 - H and H-1 are both defined from R={1} to R-{1} by...Ch. 7.3 - Explain how it follows from the definition of...Ch. 7.3 - Prove Theorem 7.3.1(b): If f is any function from...Ch. 7.3 - Prove Theorem 7.3.2(b): If f:XY is a one-to-one...Ch. 7.3 - Suppose Y and Z are sets and g:YZ is a one-to-one...Ch. 7.3 - If + f:XY and g:YZ are functions and gf is...Ch. 7.3 - If f:XY and g:YZ are function and gf is onto, must...Ch. 7.3 - If f:XY and g:YZ are function and gf is...Ch. 7.3 - If f:XY and g:YZ are functions and gf is onto,...Ch. 7.3 - Let f:WZ,g:XY , and h:YZ be functions. Must...Ch. 7.3 - True or False? Given any set X and given any...Ch. 7.3 - True or False? Given any set X and given any...Ch. 7.3 - In 26 and 27 find (gf)1,g1,f1, and f1g1 , and...Ch. 7.3 - In 26 and 27 find (gf)1,g1,f1 , and f1g1 by the...Ch. 7.3 - Prove or given a counterexample: If f:XY and g:YX...Ch. 7.3 - Suppose f:XY and g:YZ are both one-to-one and...Ch. 7.3 - Let f:XY and g:YZ. Is the following property true...Ch. 7.4 - A set is finite if, and only if,________Ch. 7.4 - To prove that a set A has the same cardinality as...Ch. 7.4 - The reflexive property of cardinality says that...Ch. 7.4 - The symmetric property of cardinality says that...Ch. 7.4 - The transitive property of cardinality say that...Ch. 7.4 - A set called countably infinite if, and only...Ch. 7.4 - A set is called countable if, and only if,_______Ch. 7.4 - In each of the following, fill in the blank the...Ch. 7.4 - The cantor diagonalization process is used to...Ch. 7.4 - When asked what it means to say that set A has the...Ch. 7.4 - Show that “there are as many squares as there are...Ch. 7.4 - Let 3Z={nZn=3k,forsomeintegerk} . Prove that Z and...Ch. 7.4 - Let O be the set of all odd integers. Prove that O...Ch. 7.4 - Let 25Z be the set of all integers that are...Ch. 7.4 - Use the functions I and J defined in the paragraph...Ch. 7.4 - (a) Check that the formula for F given at the end...Ch. 7.4 - Use the result of exercise 3 to prove that 3Z is...Ch. 7.4 - Show that the set of all nonnegative integers is...Ch. 7.4 - In 10-14 s denotes the sets of real numbers...Ch. 7.4 - In 10-14 s denotes the sets of real numbers...Ch. 7.4 - In 10-14 S denotes the set of real numbers...Ch. 7.4 - In 10—14 S denotes the set of real numbers...Ch. 7.4 - In 10—14 S denotes the set of real numbers...Ch. 7.4 - Show that the set of all bit string (string of 0’s...Ch. 7.4 - Show that Q, that set of all rational numbers, is...Ch. 7.4 - Show that Q, the set of all rational numbers, is...Ch. 7.4 - Must the average of two irrational numbers always...Ch. 7.4 - Show that the set of all irrational numbers is...Ch. 7.4 - Give two examples of functions from Z to Z that...Ch. 7.4 - Give two examples of function from Z to Z that are...Ch. 7.4 - Define a function g:Z+Z+Z+ by the formula...Ch. 7.4 - âa. Explain how to use the following diagram to...Ch. 7.4 - Prove that the function H defined analytically in...Ch. 7.4 - Prove that 0.1999….=0.2Ch. 7.4 - Prove that any infinite set contain a countable...Ch. 7.4 - Prove that if A is any countably infinite set, B...Ch. 7.4 - Prove that a disjoint union of any finite set and...Ch. 7.4 - Prove that a union of any two countably infinite...Ch. 7.4 - Use the result of exercise 29 to prove that the...Ch. 7.4 - Use the results of exercise 28 and 29 to prove...Ch. 7.4 - Prove that ZZ , the Cartesian product of the set...Ch. 7.4 - Use the results of exercises 27, 31, and 32 to...Ch. 7.4 - Let P(s) be the set of all subsets of set S, and...Ch. 7.4 - Let S be a set and P(S) be the set of all subsets...Ch. 7.4 - `The Schroeder-Bernstein theorem states the...Ch. 7.4 - Prove that if A and B are any countably infinite...Ch. 7.4 - Suppose A1,A2,A3,.... is an infinite sequence of...

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