Mathematics - II (Differential Equation) - B.Tech 2nd Semester Examination, 2025 (Old Course)

2025Semester 3Civil-CAEnd Semester
Bihar Engineering University, Patna
B.Tech 2nd Semester Examination, 2025 (Old Course)

Mathematics - II (Differential Equation)

Time: 03 HoursCode: 101202Full Marks: 70

Instructions:

  1. The marks are indicated in the right-hand margin.
  2. There are NINE questions in this paper.
  3. Attempt FIVE questions in all.
  4. Question No. 1 is compulsory.
Q.1 Choose the correct option/answer the following (Any seven question only):[14]
  1. For the differential equation, \( (x-1) \frac{d^2y}{dx^2} + \cot(\pi x) \frac{dy}{dx} + ( cosec^2 \pi x)y = 0 \) which of the following statement is true?

    1. 0 is regular and 1 is irregular
    2. 0 is irregular and 1 is regular
    3. Both 0 and 1 are regular
    4. Both 0 and 1 are irregular
  2. Let \( P_n(x) \) be the Legendre polynomial of degree \( n \ge 0 \). Then \( \int_{-1}^{1} P_n(x) dx = 2 \) if n is

    1. 0
    2. 1
    3. 2
    4. None of these
  3. \( \int_{0}^{\pi/2} \sqrt{\pi x} J_{1/2}(2x) dx = k \) then k is

    1. 0
    2. 1
    3. 2
    4. \( \sqrt{\pi} \)
  4. The solution of \( p+q=z \) is

    1. \( f(xy, y \log z) = 0 \)
    2. \( f(x+y, y+\log z) = 0 \)
    3. \( f(x-y, y-\log z) = 0 \)
    4. \( f(x/y, y/\log z) = 0 \)
  5. The complementary function of \( \frac{\partial^2 z}{\partial x^2} - 4 \frac{\partial^2 z}{\partial x \partial y} + 4 \frac{\partial^2 z}{\partial y^2} = x+y \) is

    1. \( f(y+2x) + xg(y+2x) \)
    2. \( f(y-2x) + xg(y-2x) \)
    3. \( x f(y+2x) + y g(y+2x) \)
    4. \( x f(y+2x) - y g(y+2x) \)
  6. The transformation \( w = \sin z \) is conformal

    1. at all points
    2. at all points except \( z = n\pi + \frac{\pi}{2} \), \( n=0, \pm 1, \pm 2, \dots \)
    3. at all points except \( z = n\pi + \frac{\pi}{2} \), \( n=0, 1, 2, \dots \)
    4. at all points except \( z = n\pi + \frac{\pi}{2} \), \( n=1, 2, 3, \dots \)
  7. The value of \( \int_C \frac{3z^2 + 7z + 1}{z-4} dz \), where C is \( 9x^2 + 4y^2 = 36 \) is

    1. \( 2\pi i \)
    2. 0
    3. \( 3\pi i \)
    4. \( 4\pi i \)
  8. Newton's iterative formula to find the value of \( \sqrt{N} \) is

    1. \( x_{n+1} = \frac{1}{2} (x_n - N/x_n) \)
    2. \( x_{n+1} = \frac{1}{2} (x_n - Nx_n) \)
    3. \( x_{n+1} = \frac{1}{2} (x_n + N/x_n) \)
    4. \( x_{n+1} = \frac{1}{2} (x_n + Nx_n) \)
  9. While applying Simpson's 3/8 rule the number of sub intervals should be

    1. Odd
    2. 8
    3. Even
    4. Multiple of 3
  10. In the geometrical meaning of Euler's algorithm, the curve is approximated as a

    1. Straight line
    2. Circle
    3. Parabola
    4. Ellipse
Q.2 Solve both questions :[14]
  1. Solve \( y = 2px + y^2 p^3 \).

  2. Solve \( (px-y)(py+x) = a^2 p \).

Q.3 Solve both questions :[14]
  1. Find the solution of the differential equation \( x^2 y'' - 4xy' + 6y = x^4 \cos x \), \( y(\pi)=0, y'(\pi)=1 \).

  2. State and prove the orthogonal property of Legendre polynomial.

Q.4 Solve both questions :[14]
  1. Find the solution of the following partial differential equation: \( (x^2-yz)p + (y^2-zx)q = z^2-xy \)

  2. Find the solution of the following partial differential equation: \( 2z + p^2 + qy + 2y^2 = 0 \)

Q.5 Solve both questions :[14]
  1. Find the solution of the partial differential equation \( (D - 5D' - 6)z = 6e^{6x} \log(y+5x) \).

  2. Show that the function \( f(z) = \sqrt{|xy|} \) is not analytic at the origin even though C.R. equations are satisfied thereof.

Q.6 Solve both questions :[14]
  1. Find the Taylor series expansion of the function \( f(z) = \sin z \). Also find the values of \( f^{(2n)}(0) \) and \( f^{(2n-1)}(0) \).

  2. Write the statement of Cauchy Integral formula. Hence, evaluate the integral \( \int_C \frac{z-1}{(z+1)^2(z-2)} dz \) where C is the circle \( |z-i|=2 \).

Q.7 Solve both questions :[14]
  1. Find the value of the integral \( \int_{0}^{\infty} \frac{\cos ax - \cos bx}{x^2} dx \) where \( a, b > 0 \).

  2. Discuss the rate of convergence of Bisection method.

Q.8 Solve both questions :[14]
  1. A third degree polynomial passes through the points (0,1), (1, 1), (2, 1) and (3, -2). Find the polynomial.

  2. Evaluate \( \int_{4}^{5/2} \log x \, dx \) by Simpson's 1/3 rule and Simpson's 3/8 rule, by dividing the range into 6 parts.

Q.9 Solve this question :[14]
  1. Using Euler's modified method, find numerical solution of the differential equation \( \frac{dy}{dx} = x + |\sqrt{y}| \) with \( y(0)=1 \) for \( 0 \le x \le 0.6 \), in steps of 0.2.