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ICAR AIEEA-PG Engineering Mathematics: practice questions

ICAR AIEEA-PG — Agricultural Engineering & Technology (Major Subject Group 10) · India · National Testing Agency for ICAR

Original practice questions written to the published syllabus · not past papers
10worked here, free
105written to this exam in this subject
16syllabus units

What this subject covers

The algebra, calculus, differential equations and numerical methods used in every numerical question of the degree. GATE AG gives it a fixed block of marks every year.

In the exams: GATE AG Section 1, about 12–13 marks a year (2019–26); ICAR AIEEA-PG Unit I; NCEES FE 8–12 questions; allied subject in PRC ABE

What ICAR AIEEA-PG asks from it

ICAR AIEEA-PG — Agricultural Engineering & Technology (Unit I)

Unit I combines mathematics and statistics. Expect single-answer MCQs on matrices, differentiation and integration, differential equations and numerical methods at a slightly lower computational load than GATE, often testing a standard result directly (a Laplace pair, a series sum, a Simpson's rule weight).

Where the 105 questions fall

How our questions for ICAR AIEEA-PG spread across the units of Engineering Mathematics. Difficulty: 32 easy, 52 medium, 21 hard.

Eigenvalues, eigenvectors and the Cayley-Hamilton theorem8
Vector calculus: gradient, divergence and curl8
Line, surface and volume integrals: Green, Stokes and Gauss theorems8
Laplace transforms8
Numerical solution of equations: bisection and Newton-Raphson8
Euler's theorem on homogeneous functions7
Higher-order linear ordinary differential equations7
Numerical solution of ODEs: Euler and Runge-Kutta methods7
Sequences, series and convergence6
Taylor, Maclaurin and Fourier series6
First-order ordinary differential equations6
Partial differential equations: Laplace, heat and wave equations6
Numerical integration: trapezoidal and Simpson's rules6
Matrices, determinants and systems of linear equations5
Limits, continuity and partial derivatives5
Maxima and minima of functions of several variables4

10 practice questions, worked

Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.

1 · Matrices, determinants and systems of linear equations · medium

A is a 3×3 matrix with det(A) = 5. What is det(2A⁻¹)?

  1. 40
  2. 2/5
  3. 10
  4. 8/5
Answer and working

D. 8/5

det(kA) = kⁿ det(A) for an n×n matrix, and det(A⁻¹) = 1/det(A). So det(2A⁻¹) = 2³ × (1/5) = 8/5. Using k instead of k³ gives 2/5; 40 is det(2A), forgetting the inverse; 10 multiplies 2 by 5.

Further reading: Grewal, Higher Engineering Mathematics

2 · Eigenvalues, eigenvectors and the Cayley-Hamilton theorem · medium

By the Cayley-Hamilton theorem, the matrix A = [[1, 2], [3, 4]] satisfies A² = ?

  1. 4A + 2I
  2. 5A − 2I
  3. −5A + 2I
  4. 5A + 2I
Answer and working

D. 5A + 2I

Characteristic polynomial: λ² − (trace)λ + det = λ² − 5λ − 2 (det = 4 − 6 = −2). Cayley-Hamilton says A² − 5A − 2I = 0, so A² = 5A + 2I. Direct check: A² = [[7, 10], [15, 22]] and 5A + 2I = [[7, 10], [15, 22]]. 5A − 2I comes from writing det as +2 instead of −2.

Further reading: Kreyszig, Advanced Engineering Mathematics

3 · Euler's theorem on homogeneous functions · medium

What is the degree of homogeneity of u = (x^(1/3) + y^(1/3))/(x^(1/2) + y^(1/2))?

  1. 5/6
  2. −1/6
  3. 1/6
  4. −1/3
Answer and working

B. −1/6

u(tx, ty) = t^(1/3)/t^(1/2) · u = t^(−1/6) u, so the degree is 1/3 − 1/2 = −1/6. Subtracting in the wrong order gives +1/6; adding the powers gives 5/6.

Further reading: Grewal, Higher Engineering Mathematics

4 · Sequences, series and convergence · hard

The series Σ n²/2ⁿ (n = 1 to ∞) converges by the ratio test. What is its sum?

  1. 8
  2. 4
  3. 2
  4. 6
Answer and working

D. 6

Ratio test: a(n+1)/a(n) = [(n + 1)²/n²]/2 → 1/2 < 1, so it converges. Using Σ n xⁿ = x/(1 − x)² and Σ n² xⁿ = x(1 + x)/(1 − x)³ with x = 1/2: (1/2)(3/2)/(1/8) = 6. 2 is Σ n/2ⁿ (the first-power sum); 4 comes from dropping the (1 + x) factor.

Further reading: Kreyszig, Advanced Engineering Mathematics

5 · Vector calculus: gradient, divergence and curl · easy

For any scalar field φ and vector field F with continuous second derivatives, which pair of identities holds?

  1. grad(div F) = 0 and curl(grad φ) = 0
  2. curl(grad φ) = ∇²φ and div(curl F) = 0
  3. curl(grad φ) = 0 and div(curl F) = 0
  4. div(grad φ) = 0 and curl(curl F) = 0
Answer and working

C. curl(grad φ) = 0 and div(curl F) = 0

Both follow from equality of mixed partial derivatives. div(grad φ) is the Laplacian ∇²φ, which is not zero in general (it is zero only for harmonic φ).

Further reading: Kreyszig, Advanced Engineering Mathematics

6 · Line, surface and volume integrals: Green, Stokes and Gauss theorems · medium

What is the volume of the tetrahedron bounded by the coordinate planes and the plane x + y + z = 1, found by triple integration?

  1. 1/3
  2. 1
  3. 1/2
  4. 1/6
Answer and working

D. 1/6

V = ∫₀¹ ∫₀^(1−x) ∫₀^(1−x−y) dz dy dx = ∫₀¹ (1 − x)²/2 dx = 1/6. 1/2 is the area of the base triangle; 1/3 is (1/3)·base·height with base area 1 instead of 1/2.

Further reading: Kreyszig, Advanced Engineering Mathematics

7 · First-order ordinary differential equations · easy

Which substitution turns the Bernoulli equation dy/dx + y = x y³ into a linear equation?

  1. v = y/x
  2. v = y⁻²
  3. v = y³
  4. v = y²
Answer and working

B. v = y⁻²

For dy/dx + P y = Q yⁿ the substitution is v = y^(1−n); with n = 3 that is y⁻². v = y/x is for homogeneous equations.

Further reading: Kreyszig, Advanced Engineering Mathematics

8 · Laplace transforms · easy

What is the Laplace transform of t²?

  1. 2/s²
  2. 1/s³
  3. 1/s²
  4. 2/s³
Answer and working

D. 2/s³

L{tⁿ} = n!/s^(n+1). For n = 2: 2!/s³ = 2/s³. 1/s³ forgets the n!; 2/s² uses sⁿ instead of s^(n+1).

Further reading: Kreyszig, Advanced Engineering Mathematics

9 · Partial differential equations: Laplace, heat and wave equations · easy

The PDE u_xx + 4u_xy + 4u_yy = 0 is

  1. parabolic
  2. hyperbolic
  3. not classifiable
  4. elliptic
Answer and working

A. parabolic

For A u_xx + B u_xy + C u_yy, the discriminant B² − 4AC = 16 − 16 = 0 → parabolic. Negative → elliptic (Laplace), positive → hyperbolic (wave).

Further reading: Kreyszig, Advanced Engineering Mathematics

10 · Partial differential equations: Laplace, heat and wave equations · medium

For what value of k does u = e^(−kt) sin 3x satisfy the heat equation u_t = 2u_xx?

  1. 6
  2. 18
  3. 9
  4. −18
Answer and working

B. 18

u_t = −k e^(−kt) sin 3x; u_xx = −9 e^(−kt) sin 3x. So −k = 2(−9) and k = 18. 6 uses 3 instead of 3²; 9 forgets the factor 2; −18 is a sign slip.

Further reading: Kreyszig, Advanced Engineering Mathematics

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Engineering MathematicsThe full study manual, free ICAR AIEEA-PGFormat, sections and how it has changed

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