D.An equation containing only independent variables
Correct Answer: An equation defining terms using earlier terms
Explanation:
A recurrence relation defines each term of a sequence using one or more preceding terms.
Incorrect! Try again.
2Which of the following is a recurrence relation?
Recurrence relation
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
The equation relates to the preceding term , so it is a recurrence relation.
Incorrect! Try again.
3Given and , what is ?
Recurrence relation
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
Substituting gives .
Incorrect! Try again.
4A population begins with organisms and doubles every hour. Which recurrence relation models the population after hours?
Modelling with recurrence relations
Easy
A.,
B.,
C.,
D.,
Correct Answer: ,
Explanation:
Doubling means each new population is twice the preceding population.
Incorrect! Try again.
5A person deposits dollars into an account at the end of every month, with no interest. If , which recurrence models the balance?
Modelling with recurrence relations
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
Each month, the balance increases by the fixed deposit of dollars.
Incorrect! Try again.
6A machine produces more items each day than it produced on the previous day. Which recurrence relation represents the daily production ?
Modelling with recurrence relations
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
Producing more items than the previous day corresponds to adding to the preceding term.
Incorrect! Try again.
7Which recurrence relation is homogeneous and linear with constant coefficients?
Homogeneous linear recurrence relations with constant coefficients
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
It is linear, has constant coefficients, and has no additional term independent of the sequence.
Incorrect! Try again.
8What is the characteristic equation of ?
Homogeneous linear recurrence relations with constant coefficients
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
Substituting and dividing by gives .
Incorrect! Try again.
9What are the characteristic roots of ?
Homogeneous linear recurrence relations with constant coefficients
Easy
A. and
B. and
C. and
D. and
Correct Answer: and
Explanation:
The polynomial factors as , giving roots and .
Incorrect! Try again.
10If a second-order homogeneous recurrence has distinct characteristic roots and , what is the general form of its solution?
Homogeneous linear recurrence relations with constant coefficients
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
Each distinct characteristic root contributes a term of the form to the general solution.
Incorrect! Try again.
11For the shift operator , which expression correctly defines its action on ?
Method of inverse operator to solve the non-homogeneous recurrence relation with constant coefficient
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
The forward shift operator moves the sequence index forward by one: .
Incorrect! Try again.
12If a non-homogeneous recurrence is written as , what is its formal particular solution using the inverse operator?
Method of inverse operator to solve the non-homogeneous recurrence relation with constant coefficient
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
Applying the inverse operator to both sides gives a formal expression for the particular solution.
Incorrect! Try again.
13For , which constant is a particular solution?
Method of inverse operator to solve the non-homogeneous recurrence relation with constant coefficient
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
For a constant solution , . Thus , so .
Incorrect! Try again.
14What is the ordinary generating function of a sequence ?
Generating functions
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
An ordinary generating function stores the sequence terms as coefficients of powers of .
Incorrect! Try again.
15What is the generating function of the sequence ?
Generating functions
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
The geometric series equals .
Incorrect! Try again.
16In the generating function , what is the coefficient of ?
Generating functions
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
By definition, the coefficient of in is the sequence term .
Incorrect! Try again.
17Which sequence has the generating function ?
Generating functions
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
Using the geometric-series formula, .
Incorrect! Try again.
18For with , what is the generating function ?
Solution of recurrence relation using generating functions
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
The recurrence gives the constant sequence , whose generating function is .
Incorrect! Try again.
19For with , what is the generating function ?
Solution of recurrence relation using generating functions
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
The recurrence produces , so .
Incorrect! Try again.
20For the Fibonacci recurrence with and , what is its generating function?
Solution of recurrence relation using generating functions
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
Applying the recurrence and initial values to the generating series gives .
Incorrect! Try again.
21What are the order and degree of the recurrence relation ?
Recurrence relation
Medium
A.Order and degree
B.Order and degree
C.Order and degree
D.Order and degree
Correct Answer: Order and degree
Explanation:
The largest backward shift is , so the order is . The highest power of any sequence term is , so the degree is .
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22Which sequence satisfies for , with and ?
Recurrence relation
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Substitution gives , and the formula also satisfies both initial conditions.
Incorrect! Try again.
23An account earns interest each month, after which is deposited. If is the balance after the deposit in month , which recurrence models the account?
Modelling with recurrence relations
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The previous balance first grows by the factor , and then the fixed deposit of is added.
Incorrect! Try again.
24Let be the number of binary strings of length that contain no two consecutive s. Which recurrence and initial values correctly model ?
Modelling with recurrence relations
Medium
A., ,
B., ,
C., ,
D., ,
Correct Answer: , ,
Explanation:
A valid string ends either in after any valid length- string or in after any valid length- string.
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25What is the general solution of ?
Homogeneous linear recurrence relations with constant coefficients
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The characteristic equation has distinct roots and .
Incorrect! Try again.
26Which expression is the general solution of ?
Homogeneous linear recurrence relations with constant coefficients
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The characteristic polynomial is , so the repeated root produces the terms and .
Incorrect! Try again.
27Solve given and .
Homogeneous linear recurrence relations with constant coefficients
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The roots are and . Applying and gives both coefficients equal to .
Incorrect! Try again.
28A second-order homogeneous recurrence has characteristic roots and . Which recurrence corresponds to these roots?
Homogeneous linear recurrence relations with constant coefficients
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The characteristic polynomial is , which gives .
Incorrect! Try again.
29For the recurrence , which expression is a valid particular solution?
Method of inverse operator to solve the non-homogeneous recurrence relation with constant coefficient
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Substituting gives , so .
Incorrect! Try again.
30For , which trial form accounts for resonance with the complementary solution?
Method of inverse operator to solve the non-homogeneous recurrence relation with constant coefficient
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Since already belongs to the complementary solution, multiplying the usual trial by provides an independent particular solution.
Incorrect! Try again.
31Which expression is a particular solution of ?
Method of inverse operator to solve the non-homogeneous recurrence relation with constant coefficient
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The difference equals , as required.
Incorrect! Try again.
32Solve for , given .
Method of inverse operator to solve the non-homogeneous recurrence relation with constant coefficient
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
A constant particular solution is , so . The condition gives .
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33What is the ordinary generating function of the sequence ?
Generating functions
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The geometric series identity gives .
Incorrect! Try again.
34If , which expression equals ?
Generating functions
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Removing the constant term from and dividing by shifts every remaining coefficient down by one index.
Incorrect! Try again.
35If and , what is ?
Generating functions
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The coefficient is the convolution . Equivalently, .
Incorrect! Try again.
36The generating function of a sequence is . Which formula describes its coefficients?
Generating functions
Medium
A. and for
B. and for
C. and for
D. and for
Correct Answer: and for
Explanation:
Expanding gives , so the constant term is and the coefficient of is .
Incorrect! Try again.
37Let for , with and . What is its generating function ?
Solution of recurrence relation using generating functions
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Summing the recurrence gives .
Incorrect! Try again.
38For with , which generating function represents the sequence?
Solution of recurrence relation using generating functions
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Summing for gives , which yields the stated generating function.
Incorrect! Try again.
39If , what is the coefficient in ?
Solution of recurrence relation using generating functions
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Partial fractions give , so .
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40For the recurrence with , which equation for the generating function is correct?
Solution of recurrence relation using generating functions
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Summing for gives .
Incorrect! Try again.
41Consider the recurrence with . Which statement correctly describes its solutions?
Recurrence relation
Hard
A.Every term from onward can be selected independently because the coefficient vanishes at .
B.No sequence satisfies the recurrence.
C.Exactly one sequence satisfies the recurrence.
D.Infinitely many sequences satisfy it, one for each choice of .
Correct Answer: Infinitely many sequences satisfy it, one for each choice of .
Explanation:
At , the recurrence gives . At , it reduces to , which is satisfied but leaves arbitrary. Every later term is then uniquely determined.
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42Let be the number of circular binary strings of length , with labeled positions, in which no two adjacent positions contain ; the first and last positions are also adjacent. Which recurrence and initial values are correct?
Modelling with recurrence relations
Hard
A. for , with and
B. for , with and
C. for , with and
D. for , with and
Correct Answer: for , with and
Explanation:
Circular binary strings with no adjacent s are counted by Lucas numbers. Direct counting gives and , followed by the Fibonacci-type recurrence.
Incorrect! Try again.
43Let denote the number of permutations of objects having no fixed points. Which recurrence correctly models ?
Modelling with recurrence relations
Hard
A., with and
B., with and
C., because the image of the first object can be chosen in ways before arranging all remaining objects.
D., with and
Correct Answer: , with and
Explanation:
Choose the image of one object in ways. According to whether the resulting assignment forms a -cycle, the remaining arrangement contributes or .
Incorrect! Try again.
44Solve given , , and .
Homogeneous linear recurrence relations with constant coefficients
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The characteristic polynomial is , so . Substituting the three initial values gives and .
Incorrect! Try again.
45Find the solution of with and .
Homogeneous linear recurrence relations with constant coefficients
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The roots are . Thus , and the initial values give , .
Incorrect! Try again.
46A sequence satisfies the recurrence whose characteristic polynomial is , with initial values . Under which condition does exist and remain nonzero?
Homogeneous linear recurrence relations with constant coefficients
Hard
A. and
B. and
C. and
D. and
Correct Answer: and
Explanation:
The general form is . A finite limit requires , equivalent to . The limit is , so it is nonzero exactly when .
Incorrect! Try again.
47What is the minimum-order homogeneous linear recurrence with constant coefficients that can have as a solution?
Homogeneous linear recurrence relations with constant coefficients
Hard
A.An order- recurrence with characteristic polynomial
B.An order- recurrence with characteristic polynomial
C.An order- recurrence with characteristic polynomial
D.An order- recurrence with characteristic polynomial
Correct Answer: An order- recurrence with characteristic polynomial
Explanation:
A degree- polynomial multiplying requires root with multiplicity . The term requires the additional simple root .
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48Using the shift operator , find a particular solution of equivalently .
Method of inverse operator to solve the non-homogeneous recurrence relation with constant coefficient
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
Writing gives . Hence , satisfied by .
Incorrect! Try again.
49Which expression is a particular solution of
Method of inverse operator to solve the non-homogeneous recurrence relation with constant coefficient
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
Because is a characteristic root, a linear forcing requires a quadratic trial. Substitution of gives and .
Incorrect! Try again.
50Find a particular solution of
Method of inverse operator to solve the non-homogeneous recurrence relation with constant coefficient
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The characteristic polynomial has the simple root , so resonance requires a trial . Substitution gives .
Incorrect! Try again.
51For which trial form contains the necessary terms for a particular solution without duplicating homogeneous terms?
Method of inverse operator to solve the non-homogeneous recurrence relation with constant coefficient
Hard
A.
B., since both forcing components must always be multiplied by the full resonance factor.
C.
D.
Correct Answer:
Explanation:
The operator is . The degree- polynomial forcing is resonant with root of multiplicity , giving . The term is nonresonant.
Incorrect! Try again.
52Let , , and . What is
Generating functions
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
Since , multiplication by gives coefficient .
Incorrect! Try again.
53Determine the coefficient of in
Generating functions
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The coefficient is the convolution , which simplifies to .
Incorrect! Try again.
54Suppose Which initial values and recurrence are implied?
Generating functions
Hard
A., , , and for
B., , , and for
C., , , and for
D., , , and for
Correct Answer: , , , and for
Explanation:
From , coefficient comparison gives , , , and .
Incorrect! Try again.
55Let when and otherwise. What is the ordinary generating function ?
Generating functions
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The coefficient pattern is periodic with block . Repeating this block gives .
Incorrect! Try again.
56For the Fibonacci sequence , , define Which expression equals ?
Generating functions
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The even-indexed Fibonacci numbers satisfy . With initial terms , their generating function is .
Incorrect! Try again.
57Solve with .
Solution of recurrence relation using generating functions
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The generating-function equation is . Simplification and coefficient extraction give .
Incorrect! Try again.
58Solve with and .
Solution of recurrence relation using generating functions
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The homogeneous part is , while a particular solution is . Applying and gives and .
Incorrect! Try again.
59Let and If , which formal power series is ?
Solution of recurrence relation using generating functions
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The recurrence gives . Solving the quadratic yields two branches, and only the minus branch has constant term and is a formal power series.
Incorrect! Try again.
60A sequence is defined by and Which closed form is correct?
Solution of recurrence relation using generating functions
Hard
A. and for
B. and for
C. and for
D. and for
Correct Answer: and for
Explanation:
Generating functions give . Its coefficients are and for .
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