The general solution of the differential equation d x 2 d 2 y + 2 dx dy − 5 y = 0 in terms of arbitrary constants K1 and K2 is
A. K1 e(-1 + √6)x + K2 e(-1 - √6)x
B. K1 e(-1 + √8)x + K2 e(-1 - √8)x
C. K1 e(-2 + √6)x + K2 e(-2 - √6)x
D. K1 e(-2 + √8)x + K2 e(-2 - √8)x
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General solution of the Cauchy-Euler equation x 2 d x 2 d 2 y − 7 x dx dy + 16 y = 0 is
A. y = c1 x2 + c2 x4
B. y = c1 x2 + c2 x-4
C. y = (c1 + c2 ln x) x4
D. y = c1 x4 + c2 x-4 ln x
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Biotransformation of an organic compound having concentration (x) can be modeled using an ordinary differential equation dt dx + k x 2 = 0 , where k is the reaction rate constant. If x = a at t = 0, the solution of the equation is
A. x = ae-kt
B. x 1 = a 1 + kt
C. x = a(1 - e-kt )
D. x = a + kt
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The solution of initial value problem; ∂ x ∂ u = 2 ∂ t ∂ u + u, where u(x, 0) = 6e-3x is
A. u = 6e-3x + t
B. u = 6e-(2x + 2t)
C. u = 6e-(3x + 2t)
D. None of the above
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A function n(x) satisfies the differential equation d x 2 d 2 n ( x ) − L 2 n ( x ) = 0 where L is a constant. The boundary conditions are: n(0) = K and n(∞ ) = 0. The solution to this equation is
A. n(x) = K exp(x/L)
B. n(x)= K exp(-x/√L)
C. n(x) = K2 exp(-x/L)
D. n(x) = K exp(-x/L)
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The solutions of differential equation d x 2 d 2 y + dx 2dy + 2 y = 0 are
A. e-(1 + i)x , e-(1 - i)x
B. e(1 + i)x , e(1 - i)x
C. e-(1 + i)x , e(1 - i)x
D. e(1 + i)x , e-(1 - i)x
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It is given that y'' + 2y' + y = 0, y(0) = 0, y(1) = 0. What is y (0.5)?
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A function y(t), such that y(0) = 1 and y(1) = 3e-1 , is a solution of the differential equation d t 2 d 2 y + 2 dt dy + y = 0. Then y(2) is
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A curve passes through the point (x = 1, y = 0) and satisfies the differential equation dx dy = 2 y x 2 + y 2 + x y . The equation that describes the curve is
A. ln ( 1 + x 2 y 2 ) = x − 1
B. 2 1 ln ( 1 + x 2 y 2 ) = x − 1
C. ln ( 1 + x y ) = x − 1
D. 2 1 ln ( 1 + x y ) = x − 1
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The differential equation dx dy + 4 y = 5 is valid in the domain 0 ≤ x ≤ 1 with y(0) = 2.25. The solution of differential equation is
A. y = e-4x + 1.25
B. y = e-4x + 5
C. y = e4x + 5
D. y = e4x + 1.25
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The degree of the differential equation d t 2 d 2 x + 2 x 3 = 0 is
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The solution for the differential equation
d t 2 d 2 x = − 9 x with initial conditions x(0) = 1 and
dt dx t = 0 = 1 , is
A. t2 + t + 1
B. sin 3 t + 3 1 cos 3 t + 3 2
C. 3 1 sin 3 t + cos 3 t
D. cos 3t + t
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Consider the differential equation: dx dy = ( 1 + y 2 ) x .
The general solution with constant c is
A. y = tan 2 x + tan c
B. y = tan 2 ( 2 x + c )
C. y = tan 2 ( 2 x ) + c
D. y = tan ( 2 x 2 + c )
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A spherical naphthalene ball exposed to the atmosphere loses volume at a rate proportional to its instantaneous surface area due to evaporation. If the initial diameter of the ball is 2 cm and the diameter reduces to 1 cm after 3 months, the ball completely evaporates in
A. 6 months
B. 9 months
C. 12 months
D. infinite time
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The particular solution of the initial value problem given below is
d x 2 d 2 y + 12 dx dy + 36 y = 0 with y(0) = 3 and
dx dy x = 0 = − 36 A. (3 - 18x)e-6x
B. (3 + 25x)e-6x
C. (3 + 20x)e-6x
D. (3 - 12x)e-6x
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The solution to x2 y'' + y' - y = 0 is
A. y = c1 x2 + c2 x-3
B. y = c1 + c2 x-2
C. y = c 1 x + x c 2
D. y = c1 x + c2 x4
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Consider the following difference equation
x ( ydx + xdy ) cos x y = y ( xdy − ydx ) sin x y
Which of the following is the solution of the above equation (c is an arbitrary constant)?
A. y x cos x y = c
B. y x sin x y = c
C. xy cos x y = c
D. xy sin x y = c
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Consider the differential equation x 2 d x 2 d 2 y + x dx dy − y = 0. Which of the following is a solution to this differential equation for x > 0 ?
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The complete integral of (z - px - qy)3 = pq + 2(p2 + q)2 is
A. z = ax + by + \root 3 \of pq + 2 ( p 2 + q ) 2
B. z = ax + by + \root 3 \of ab + 2 ( a 2 + b ) 2
C. z = ax + by + \root 3 \of ab + \root 3 \of 2 ( a 2 + b ) 2
D. z = ax + by + c
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The integrating factor for differential equation dt dP + k 2 P = k 1 L 0 e − k 1 t is
A. e-k1 t
B. e-k2 t
C. ek1 t
D. ek2 t
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