Q01. The general solution of the differential equation () 2 2 xdy - ydx = x + y dy is:
A () y x tan x C = +
B () x ytan x C = +
C () x ytan y C = +
D () y x tan y C = +
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Correct answer: () y x tan y C = +
Q02. If a curve y = (x) f passes through the point () 1, -1 and satisfies the differential equation () y 1+ xy dx = x dy, then -1 2 f is equal to:
A −4/5
B 2/5
C 4/5
D −2/5
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Correct answer: 4/5
English Bihar (TRE 1.0) -2023
Q03. The integral surface satisfying the equation ∂ ∂ 2 2 z z y + x = x + y x y and passing through the curve x = 1 – t, y = 1 + t, z = 1 + t2 is
A z = xy + () 2 2 2 1 x y 2 −
B z = xy + () 2 2 2 1 x y 4 −
C z = xy + () 2 2 2 1 x y 8 −
D More than one of the above
E None of the above
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Correct answer: z = xy + () 2 2 2 1 x y 8 −
English Bihar (TRE 1.0) -2023
Q04. Let the general integral of the partial differential equation () () () ∂ ∂ 2 z z 2xy -1 + z - 2x = 2 x - yz z y be given by F(u, v) = 0, where F: R2 → → R is a continuously differentiable function. (R is the set of all real numbers and R2 = {(x, y): x, y ∈ R}) Then which of the following is true?
A u = x2 + y2 + z, v = xz + y
B u = x2 + y2 – z, v = xz – y
C u = x2 – y2 + z, v = yz + x
D More than one of the above
E None of the above
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Correct answer: u = x2 + y2 + z, v = xz + y
English Bihar (TRE 1.0) -2023
Q05. The partial differential equation () 2 2 2 ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ 2 2 u u u 1 u u x + x - y - y + - = 0 x y 4 y x x y is
A hyperbolic along the line x + y = 0
B elliptic along the line x - y = 0
C parabolic along the line x + y = 0
D More than one of the above
E None of the above
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Correct answer: parabolic along the line x + y = 0
English Bihar (TRE 1.0) -2023
Q06. Consider the wave equation ∂ ∂ 2 2 u u = 4,0 < x < π,t > 0 t x with u (0, t) = u (π, t) = 0, u(x, 0) = sin x and ∂ u = 0 t at t = 0. Then u π, 2 2 is
A 2
B 1
C – 1
D More than one of the above
E None of the above
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Correct answer: – 1
English Bihar (TRE 1.0) -2023
Q07. The equation (αxy3 + y cos x)dx + (x2 y2 + βsinx) dy = 0 is exact for
A α = 2, 1 3 β =
B α = 1, β = 3 2
C α = 1, β = 2 3
D More than one of the above
E None of the above
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Correct answer: α = 2, 1 3 β =
English Bihar (TRE 1.0) -2023
Q08. An integrating factor of x () -2x dy + 3x +1 y = xe dx is
A xe3x
B 3xex
C xex
D More than one of the above
E None of the above
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Correct answer: xe3x
English Bihar (TRE 1.0) -2023
Q09. The differential equation representing the family of circles touching y-axis at the origin is
A linear and of first order
B linear and of second order
C non-linear and of first order
D More than one of the above
E None of the above
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Correct answer: non-linear and of first order
English Bihar (TRE 1.0) -2023
Q10. Let, f, g: [– 1, 1] → → → R, f(x) = x3, g(x) = x2 |x|. Then
A f and g are linearly independent on [– 1, 1]
B f and g are linearly dependent on [–1, 1]
C f(x) g'(x) – f'(x)g(x) is not identically zero on [– 1, 1]
D More than one of the above
E None of the above
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Correct answer: f and g are linearly independent on [– 1, 1]
Q11. If a and b are two odd prime numbers such that a > b, then a2 – b2 is:
A an odd prime number
B an odd number
C an even number
D a prime number
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Correct answer: an even number
Q12. 3.13113111311113... is
A an irrational number
B a whole number
C an integer
D a rational number
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Correct answer: an irrational number
Q13. Solution of the differential equation dy ycot x 4x cosecx dx + =, is:
A 2 ysin x 2x c = +
B 2 ysin x x c = +
C 2 ysin x x c + =
D 2 ysin x 2x c + =
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Correct answer: 2 ysin x 2x c = +
Q14. The solution of the differential equation () 2 2 dy 1 x 1 y 0 dx + + + =, is:
A 1 1 tan x tan y c − − − =
B 1 1 tan y tan x c − − ± =
C 1 1 tan y tan x c − − − =
D 1 1 tan x tan y c − − + =
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Correct answer: 1 1 tan x tan y c − − + =
Q15. A solution of the differential equation x dy -y dx = 0 represents:
A a rectangular hyperbola
B parabola whose vertex is at origin.
C straight line passing through origin.
D A circle whose centre is at the origin.
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Correct answer: straight line passing through origin.
Q16. Which of the following equation is homogeneous differential equation?
A (x2 +xy) dy = (x2 + y) dx
B y dy y x cos ycos x x dx x = +
C dy y x 1 xsin 0 dx x − + =
D 2 dy x x 2y xy dx = − +
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Correct answer: y dy y x cos ycos x x dx x = +
Q17. Which of the following is a linear differential equation?
A (y + x) y' + y = 1
B 3y' + (x + 4) y = x2 + y''
C y''' = cos (2y)
D () 4 y y xy"' cosx e + + =
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Correct answer: () 4 y y xy"' cosx e + + =
Q18. The solution of the differential equation (x + y + 1) dy 1 dx = is:
A x = cey + y + 2
B x = cey − y + 2
C x = cey − y − 2
D x = cey + y − 2
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Correct answer: x = cey − y − 2
Q19. The order and degree of the differential equation y = dy 2 x dy dx + is:
A 1, 2
B 1, 3
C 2, 1
D 1, 1
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Correct answer: 1, 2
Q20. Solution of the differential equation (x+2y3)dy=y dx, is:
A y=x3 +c
B x=y2 +c
C x=y3 +cy
D y=x2 +c
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Correct answer: x=y3 +cy