Partial Differential Equations
45 questions across 3 topics. Also examined in CNET.
Lagrange and Charpit Methods, Cauchy Problem for First Order PDEs
- 68PDE — surfaces orthogonal to xyz=cMSET June 2025Lagrange and Charpit Methods, Cauchy Problem for First Order PDEsMedium
- 69PDE — data on a characteristic curveMSET June 2025Lagrange and Charpit Methods, Cauchy Problem for First Order PDEsMedium
- 70PDE — uniqueness of general and complete integralsMSET June 2025Lagrange and Charpit Methods, Cauchy Problem for First Order PDEsMedium
- 71PDE — characteristic curves and envelopesMSET June 2025Lagrange and Charpit Methods, Cauchy Problem for First Order PDEsMedium
- 72PDE — integrability of Pfaffian equationsMSET June 2025Lagrange and Charpit Methods, Cauchy Problem for First Order PDEsMedium
- 74PDE — envelope of planes through the originMSET June 2025Lagrange and Charpit Methods, Cauchy Problem for First Order PDEsMedium
- 69The PDE of every surface of revolution about the x-axisMSET April 2024Lagrange and Charpit Methods, Cauchy Problem for First Order PDEsMedium
- 71Envelope of a family of unit spheres — the characteristic is a great circleMSET April 2024Lagrange and Charpit Methods, Cauchy Problem for First Order PDEsHard
- 72Naming the arbitrary-function solution of a first-order PDEMSET April 2024Lagrange and Charpit Methods, Cauchy Problem for First Order PDEsMedium
- 68The characteristics of yp-xq=0 are exactly the shared intersection circlesMSET March 2023Lagrange and Charpit Methods, Cauchy Problem for First Order PDEsEasy
- 70A transversal curve gives a unique paraboloid of revolutionMSET March 2023Lagrange and Charpit Methods, Cauchy Problem for First Order PDEsMedium
- 72Integral surfaces and characteristic curves — a two-way theoremMSET March 2023Lagrange and Charpit Methods, Cauchy Problem for First Order PDEsMedium
- 74Pfaffian and Lagrange normals describe the same surfacesMSET March 2023Lagrange and Charpit Methods, Cauchy Problem for First Order PDEsMedium
- 31Eliminating two constants from z=ae^bxsin(by) — Laplace's equation appearsMSET September 2021Lagrange and Charpit Methods, Cauchy Problem for First Order PDEsMedium
- 31The defining PDE for axial symmetry about the z-axisMSET June 2019Lagrange and Charpit Methods, Cauchy Problem for First Order PDEsMedium
- 46Integrability of a Pfaffian equation: XcdotcurlX=0MSET January 2018 Paper IILagrange and Charpit Methods, Cauchy Problem for First Order PDEsEasy
- 47Lagrange's method: xy and x^2+y^2+z^2 are first integralsMSET January 2018 Paper IIILagrange and Charpit Methods, Cauchy Problem for First Order PDEsMedium
- 48Coefficients of zx,zy involving z make the PDE quasi-linearMSET January 2018 Paper IIILagrange and Charpit Methods, Cauchy Problem for First Order PDEsEasy
- 49z=ae^bxsin by is harmonicMSET April 2017 Paper IILagrange and Charpit Methods, Cauchy Problem for First Order PDEsEasy
- 50Check the complete integral: p=2a/(z+b), q=2/(z+b)MSET April 2017 Paper IILagrange and Charpit Methods, Cauchy Problem for First Order PDEsMedium
- 44Eliminating f from z=f(x^2+y^2+z^2)MSET April 2017 Paper IIILagrange and Charpit Methods, Cauchy Problem for First Order PDEsEasy
- 45A product pq of derivatives makes equation (ii) non-linearMSET April 2017 Paper IIILagrange and Charpit Methods, Cauchy Problem for First Order PDEsEasy
- 46Orthogonal surfaces: z(3z+1)(p+q)=x+y, through the given circleMSET April 2017 Paper IIILagrange and Charpit Methods, Cauchy Problem for First Order PDEsHard
Separation of Variables (Laplace, Heat and Wave Equations)
- 68Lagrange's PDE — spotting the invariant that isn't actually invariantMSET April 2024Separation of Variables (Laplace, Heat and Wave Equations)Hard
- 70Compatibility of a pair of first-order PDEsMSET April 2024Separation of Variables (Laplace, Heat and Wave Equations)Hard
- 75The compatibility condition for two first-order PDEsMSET April 2024Separation of Variables (Laplace, Heat and Wave Equations)Hard
- 73Compatibility means a genuinely shared solutionMSET March 2023Separation of Variables (Laplace, Heat and Wave Equations)Easy
- 32A repeated-characteristic-root PDEMSET September 2021Separation of Variables (Laplace, Heat and Wave Equations)Medium
- 65Neumann problems for Laplace's equation determine u only up to a constantMSET September 2021Separation of Variables (Laplace, Heat and Wave Equations)Medium
- 66Classifying a variable-coefficient second-order PDE — the maximal hyperbolic regionMSET September 2021Separation of Variables (Laplace, Heat and Wave Equations)Easy
- 32The complete integral of f(p,q)=0MSET December 2020Separation of Variables (Laplace, Heat and Wave Equations)Easy
- 65Uniqueness for the Dirichlet problem via the maximum principleMSET December 2020Separation of Variables (Laplace, Heat and Wave Equations)Medium
- 32Factoring the wave operator partialx^2-partialy^2MSET June 2019Separation of Variables (Laplace, Heat and Wave Equations)Easy
- 83The Euler equation for a Dirichlet-type surface functional is Poisson's equationMSET June 2019Separation of Variables (Laplace, Heat and Wave Equations)Easy
- 45Insulated ends ux=0 become Neumann conditions on XMSET January 2018 Paper IIISeparation of Variables (Laplace, Heat and Wave Equations)Easy
Classification of Second Order PDEs
- 73PDE — where yuxx+2xyuxy+xuyy is hyperbolicMSET June 2025Classification of Second Order PDEsEasy
- 75PDE — types of the classical equationsMSET June 2025Classification of Second Order PDEsEasy
- 73Classifying a variable-coefficient second-order PDEMSET April 2024Classification of Second Order PDEsEasy
- 74Classifying uxx+yuyy=0 on y0MSET April 2024Classification of Second Order PDEsEasy
- 75Classifying a variable-coefficient PDE via its non-negative discriminantMSET March 2023Classification of Second Order PDEsEasy
- 67PDE type is a coordinate-independent invariantMSET December 2020Classification of Second Order PDEsMedium
- 66A negative discriminant from the Laplacian's principal part gives elliptic typeMSET June 2019Classification of Second Order PDEsEasy
- 45The discriminant B^2-AC vanishes identically: parabolicMSET January 2018 Paper IIClassification of Second Order PDEsEasy
- 45B^2-AC=1-4<0: ellipticMSET April 2017 Paper IIClassification of Second Order PDEsEasy
- 7d'Alembert-type solutions f(x+2y)+g(x-2y) satisfy uyy=4uxxMSET April 2017 Paper IIIClassification of Second Order PDEsEasy