1Which of the following is a first-order linear differential equation in ?
Introduction to linear differential equation
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
A first-order linear differential equation contains and its first derivative only to the first power.
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2What is the standard form of a first-order linear differential equation?
Introduction to linear differential equation
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
The standard first-order linear form is .
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3In a linear differential equation, the dependent variable and its derivatives occur with what power?
Introduction to linear differential equation
Easy
A.Second power only
B.Any integer power
C.Zero power only
D.First power only
Correct Answer: First power only
Explanation:
A differential equation is linear when the dependent variable and its derivatives occur only to the first power.
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4What is the integrating factor for ?
Solution of linear differential equation
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
For the standard linear equation, the integrating factor is .
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5For , which is the general solution?
Solution of linear differential equation
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
The equation gives , whose general solution is .
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6For , the solution is obtained using which factor?
Solution of linear differential equation
Easy
A.Separating factor
B.Complementary factor
C.Characteristic factor
D.Integrating factor
Correct Answer: Integrating factor
Explanation:
Multiplying the equation by the integrating factor converts its left side into a derivative of a product.
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7Two functions and are linearly dependent if one can be written as what?
Linear dependence and linear independence of solution
Easy
A.The derivative of the other
B.A constant multiple of the other
C.The integral of the other
D.The square of the other
Correct Answer: A constant multiple of the other
Explanation:
Two functions are linearly dependent when constants, not both zero, can combine them to give zero.
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8Which pair of functions is linearly independent?
Linear dependence and linear independence of solution
Easy
A. and
B. and
C. and
D. and
Correct Answer: and
Explanation:
The functions and are not constant multiples of each other, so they are linearly independent.
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9The Wronskian is commonly used to test the linear dependence of which functions?
Linear dependence and linear independence of solution
Easy
A.A set of constants
B.A set of variables
C.A set of functions
D.A set of equations
Correct Answer: A set of functions
Explanation:
The Wronskian is a determinant formed from functions and their derivatives to study their linear dependence.
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10For two functions, the Wronskian is written as which expression?
Linear dependence and linear independence of solution
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
For two functions, the Wronskian is the determinant .
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11In differential operator notation, what does represent?
Method of solution of linear differential equation using differential operator
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
The differential operator is defined by .
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12How is the equation written using ?
Method of solution of linear differential equation using differential operator
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
Replacing by and by gives .
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13What is the auxiliary equation of ?
Method of solution of linear differential equation using differential operator
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
The auxiliary equation is obtained by replacing with , giving .
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14The complementary function of a homogeneous differential equation is obtained from its what?
Method of solution of linear differential equation using differential operator
Easy
A.Particular integral
B.Auxiliary equation
C.Initial condition
D.Boundary value
Correct Answer: Auxiliary equation
Explanation:
The roots of the auxiliary equation determine the complementary function.
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15For , what are the roots of the auxiliary equation?
Solution of second order homogeneous linear differential equation with constant coefficient
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
The auxiliary equation is , so the roots are and .
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16If the auxiliary equation has two distinct real roots and , what is the complementary function?
Solution of second order homogeneous linear differential equation with constant coefficient
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
Each distinct real root gives a solution , so the complementary function is their linear combination.
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17If the repeated root of the auxiliary equation is , what is the complementary function?
Solution of second order homogeneous linear differential equation with constant coefficient
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
For a repeated root , the two independent solutions are and .
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18If the roots are , what is the real complementary function?
Solution of second order homogeneous linear differential equation with constant coefficient
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
Complex roots produce the real solutions and .
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19For a third-order homogeneous linear differential equation, how many arbitrary constants usually appear in the general solution?
Solution of higher order homogeneous linear differential equations with constant coefficient
Easy
A.Four
B.Three
C.One
D.Two
Correct Answer: Three
Explanation:
An th-order linear differential equation generally has arbitrary constants in its general solution.
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20For , which is the auxiliary equation?
Solution of higher order homogeneous linear differential equations with constant coefficient
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
Replacing by in gives the auxiliary equation .
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21Which of the following is a linear differential equation in ?
Introduction to linear differential equation
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
A differential equation is linear in when and its derivatives occur only to the first power and are not multiplied together or placed inside nonlinear functions.
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22What is the order and degree of the differential equation ?
Introduction to linear differential equation
Medium
A.Order , degree
B.Order , degree
C.Order , degree
D.Order , degree
Correct Answer: Order , degree
Explanation:
The highest derivative is , so the order is . Its highest power is , so the degree is .
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23Solve .
Solution of linear differential equation
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The integrating factor is . Hence , giving and therefore .
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24For , find the general solution of .
Solution of linear differential equation
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Dividing by gives . The integrating factor is , so , which leads to .
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25The solution of satisfying is:
Solution of linear differential equation
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The complementary solution is . A particular solution is , so . Using gives .
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26Using the Wronskian, determine whether and are linearly independent.
Linear dependence and linear independence of solution
Medium
A.Independent because the Wronskian is
B.Dependent because one function contains
C.Independent because the Wronskian is
D.Dependent because the Wronskian is zero
Correct Answer: Independent because the Wronskian is
Explanation:
The Wronskian is , which is nonzero. Therefore, the functions are linearly independent.
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27Which set of functions is linearly independent on every interval?
Linear dependence and linear independence of solution
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The functions are distinct powers and form a linearly independent set. Each of the other sets consists of scalar multiples of one function.
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28If two solutions of a second-order homogeneous linear differential equation have a nonzero Wronskian at one point, what follows?
Linear dependence and linear independence of solution
Medium
A.They are linearly dependent
B.They are linearly independent
C.They are necessarily identical
D.They must both be constant
Correct Answer: They are linearly independent
Explanation:
A nonzero Wronskian at a point proves that no nontrivial constant combination of the two solutions can vanish identically.
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29In operator notation, the equation can be written as:
Method of solution of linear differential equation using differential operator
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Since , the differential equation has the stated operator form.
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30If , then the operator applied to gives:
Method of solution of linear differential equation using differential operator
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Expanding the operator gives . Therefore, its application to is .
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31The complementary function of is:
Method of solution of linear differential equation using differential operator
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The auxiliary equation is , which factors as . Thus, the complementary function is .
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32The general solution of is:
Solution of second order homogeneous linear differential equation with constant coefficient
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The auxiliary equation is , a repeated root. Therefore, the solution is .
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33Solve .
Solution of second order homogeneous linear differential equation with constant coefficient
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The auxiliary roots are . Complex roots give .
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34For , with and , the particular solution is:
Solution of second order homogeneous linear differential equation with constant coefficient
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The general solution is . The initial conditions give and , so and .
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35Which differential equation has the complementary function ?
Solution of second order homogeneous linear differential equation with constant coefficient
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The repeated root corresponding to is . Its auxiliary equation is .
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36The general solution of is:
Solution of higher order homogeneous linear differential equations with constant coefficient
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The auxiliary equation factors as . The three distinct roots produce the stated exponential terms.
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37The complementary function of is:
Solution of higher order homogeneous linear differential equations with constant coefficient
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The root is repeated twice, giving . The distinct root gives .
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38The general solution of is:
Solution of higher order homogeneous linear differential equations with constant coefficient
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The auxiliary equation has roots . These yield the exponential and trigonometric terms shown.
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39For , how many arbitrary constants appear in the complementary function?
Solution of higher order homogeneous linear differential equations with constant coefficient
Medium
A.Six
B.Four
C.Five
D.Three
Correct Answer: Five
Explanation:
The equation is of order . The repeated complex roots contribute four constants, and the root contributes one more, for a total of five.
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40The general solution of is:
Solution of higher order homogeneous linear differential equations with constant coefficient
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The auxiliary polynomial factors as . Thus, is repeated and is distinct, giving the stated solution.
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41Which of the following is a linear differential equation in , even though its coefficients are variable?
Introduction to linear differential equation
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
A differential equation is linear in when and its derivatives occur only to the first power and are not multiplied together. The coefficients may depend on .
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42For which value of is the equation not defined as a linear differential equation on the entire interval ?
Introduction to linear differential equation
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The coefficient is undefined at , which lies in . Thus the equation is not defined throughout that interval regardless of ; among the choices, also makes the leading coefficient vanish at the same singular point.
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43Find the general solution of on an interval not containing .
Solution of linear differential equation
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The integrating factor is . Hence , so , giving the stated solution.
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44The initial-value problem , , has a unique solution on an interval provided which condition holds?
Solution of linear differential equation
Hard
A. and are continuous on
B. is differentiable and is continuous on
C. is bounded and is differentiable on
D. is continuous on and is bounded on
Correct Answer: and are continuous on
Explanation:
Continuity of both and on guarantees existence and uniqueness for the first-order linear initial-value problem throughout .
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45Solve subject to .
Solution of linear differential equation
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
Using the integrating factor gives . Therefore , and gives .
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46On an interval containing , which pair of functions is linearly independent?
Linear dependence and linear independence of solution
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The relation reduces to for every , forcing . Thus the pair is independent.
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47Let and be solutions of a second-order homogeneous linear equation on an interval . If their Wronskian satisfies at one point , what follows under the usual continuity assumptions?
Linear dependence and linear independence of solution
Hard
A.They are linearly dependent on
B.Their equation must have constant coefficients
C.They are independent only at
D.They become independent away from
Correct Answer: They are linearly dependent on
Explanation:
Abel's identity implies that the Wronskian is either identically zero or never zero on an interval for solutions of the same second-order linear homogeneous equation. A zero at one point therefore implies dependence on .
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48For and , which statement about their Wronskian is correct?
Linear dependence and linear independence of solution
Hard
A. for all
B. for all
C. for all
D. for all
Correct Answer: for all
Explanation:
Using , with , gives .
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49If , which factorization is correct for the operator ?
Method of solution of linear differential equation using differential operator
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The characteristic polynomial factors as , giving the stated operator factorization.
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50For the equation , which particular integral is valid?
Method of solution of linear differential equation using differential operator
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
Since is a simple root of , use . Substitution gives , so .
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51Using operator notation, determine a particular integral for .
Method of solution of linear differential equation using differential operator
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The forcing frequency is resonant with the roots . Direct substitution of gives , hence .
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52For , which set forms the complete complementary solution?
Method of solution of linear differential equation using differential operator
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The characteristic roots are with multiplicity two and with multiplicity one. Repeated roots produce and .
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53Find the general solution of .
Solution of second order homogeneous linear differential equation with constant coefficient
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The auxiliary equation is , whose roots are . Therefore the real solution has the stated exponential-trigonometric form.
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54The solution of satisfying and is:
Solution of second order homogeneous linear differential equation with constant coefficient
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The repeated root is , so . The initial conditions give and , hence .
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55Which equation has a general solution containing both exponential decay and oscillation with angular frequency ?
Solution of second order homogeneous linear differential equation with constant coefficient
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
Its roots are . Thus solutions decay as and oscillate with angular frequency .
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56For , the roots are and . What are and ?
Solution of second order homogeneous linear differential equation with constant coefficient
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The characteristic polynomial is . Comparing coefficients yields and .
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57Find the complementary solution of .
Solution of higher order homogeneous linear differential equations with constant coefficient
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The auxiliary equation is . Each root has multiplicity two, producing both and terms.
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58Determine the real general solution of .
Solution of higher order homogeneous linear differential equations with constant coefficient
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The characteristic polynomial factors as . Since , this option is not correct.
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59Which is the correct real general solution of ?
Solution of higher order homogeneous linear differential equations with constant coefficient
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The roots of are . Combining conjugate roots gives the two exponential-trigonometric pairs, along with the root .
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60For the characteristic roots with multiplicity three and each with multiplicity two, what is the order of the differential equation and how many arbitrary constants occur?
Solution of higher order homogeneous linear differential equations with constant coefficient
Hard
A.Order , with arbitrary constants
B.Order , with arbitrary constants
C.Order , with arbitrary constants
D.Order , with arbitrary constants
Correct Answer: Order , with arbitrary constants
Explanation:
The root contributes to the order. The conjugate pair contributes real dimensions because each complex root has multiplicity two. Thus the total is .
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