Q.The order and degree of the differential equation y′+(y′′)2=(x+y′′)2 are :
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🔒 Start your 14-day free trial to unlock the full solution →Concept understanding — Order and Degree of a Differential Equation
A differential equation is any equation that contains at least one derivative — ordinary or partial — of an unknown function. If only ordinary derivatives of a function of a single independent variable appear, it is an Ordinary Differential Equation (ODE); if partial derivatives of a function of two or more independent variables appear, it is a Partial Differential Equation (PDE). This chapter deals only with ODEs.
Order. The order of a differential equation is the order of the highest derivative that appears in it. If the highest derivative of y present is the kth derivative, the order is k (a positive integer). For example, dx3d3y−5dx2d2y+4dxdy=0 has order 3.
Degree. The degree is defined only once the equation has been written in polynomial form in its derivatives — every derivative free of fractional powers or roots, and the highest-order derivative not sitting inside a transcendental function (sine, log, exponential, …) or having a coefficient that is itself transcendental in the derivatives. Once in that form, the degree is the integral power to which the highest-order derivative is raised.
Working method.
- If radicals or fractional powers appear on a derivative, isolate that term and raise both sides to the appropriate power to clear it (square, cube, …) — this can raise or lower the apparent order/degree, so always simplify to the true polynomial form first.
- If the equation contains an integral of y (not a derivative), differentiate the whole equation once more with respect to x to eliminate the integral sign before reading off order and degree. …
Expand (x+y′′)2=x2+2xy′′+(y′′)2. Substituting, y′+(y′′)2=x2+2xy′′+(y′′)2, so the (y′′)2 terms cancel, leaving y′=x2+2xy′′, i.e. 2xy′′−y′+x2=0. The highest-order derivative present …
After cancelling the (y′′)2 terms on both sides, the equation reduces to one containing y′′ to the first power, so order = 2 and degree = 1.
- Expand the right-hand side: (x+y′′)2=x2+2xy′′+(y′′)2.
- Substitute into the given equation: y′+(y′′)2=x2+2xy′′+(y′′)2.
- Cancel (y′′)2 from both sides: y′=x2+2xy′′.
- Rearranged: 2xy′′−y′+x2=0. This is now a polynomial equation in the derivatives, free of radicals/fractions involving them. …
Showing the 12 most recent of 24 on this concept.
- CBSE 2026Set ANNUAL1 markQ.Write the degree of the differential equation (y′′′)2+3(y′′)3+3xy′+5y=0
›Reveal solutionSolution
The degree is the power of the highest-order derivative, once the equation is a polynomial in derivatives (no radicals/fractions of derivatives).
Given: (y′′′)2+3(y′′)3+3xy′+5y=0.
…
- CBSE 2026Set ANNUAL1 markMCQQ.State whether the following statement is true or false: Order and degree of a differential equation are always positive integers.(a) True(b) False
›Reveal solutionSolution
Order = highest derivative order and degree = power of the highest-order derivative (equation cleared of radicals/fractions in the derivatives); each is a positive integer, so the statement is True.
By definition, the order of a differential equation is the order of the highest derivative it contains — this is always a whole counting number, i.e. a positive integer (1,2,3,…).
…
- CBSE 2025Set ANNUAL1 markQ.Write the order of the differential equation 1+(dxdy)2=(dx2d2y)3/2
›Reveal solutionSolution
The order of a differential equation is the order of the highest derivative appearing in it.
The given differential equation is
1+(dxdy)2=(dx2d2y)3/2
…
- CBSE 2025Set ANNUAL1 markMCQQ.The order and degree of the differential equation dxdy−4dxdy−7x=0 are respectively :(a) 1,2(b) 2,1(c) 2,2(d) 1,1
›Reveal solutionSolution
Isolating the radical and squaring turns the equation into a polynomial in dy/dx; the power of the highest derivative after clearing the radical gives the degree.
- Given dxdy−4dxdy−7x=0. Let p=dxdy.
- Isolate the radical: p=4p+7x.
- Square both sides to remove the radical (a fractional power of a derivative is not allowed for degree to be defined): p=(4p+7x)2=16p2+56px+49x2.
- Rearranged: 16p2+(56x−1)p+49x2=0 — a polynomial equation in p=dxdy. …
- CBSE 2025Set ANNUAL1 markMCQQ.The order and degree of the differential equation (dx2d2y)2+(dxdy)2=ax are ______ respectively.(a) 1, 1(b) 1, 2(c) 2, 2(d) 2, 1
›Reveal solutionSolution
The highest derivative is dx2d2y (order 2), and it appears raised to power 2 (degree 2).
The equation is
(dx2d2y)2+(dxdy)2=ax.
The highest-order derivative appearing is dx2d2y, so the order is 2.
…
- CBSE 2025Set MARCH1 markMCQQ.The differential equation (dydx)3+2y1/2=x is :(a) of order 1 and degree 6(b) of order 2 and degree 1(c) of order 1 and degree 2(d) of order 1 and degree 3
›Reveal solutionSolution
The only derivative present is dydx (order 1), raised to power 3 in a polynomial form, so the degree is 3; option (d).
Order. The equation (dydx)3+2y1/2=x contains only the first derivative dydx, so the order is 1.
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- CBSE 2024Set ANNUAL1 markMCQQ.Order and degree of the differential equation y = dy/dx + c/(dy/dx) are(a) 1, 2(b) 2, 2(c) 1, 1(d) 2, 1
›Reveal solutionSolution
Rewrite the equation as a polynomial in dy/dx; the highest power of the highest-order derivative gives the degree.
Let p=dy/dx. The equation y=p+c/p becomes, after multiplying through by p:
yp=p2+c⇒p2−yp+c=0
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- CBSE 2024Set ANNUAL1 markMCQQ.State whether the following statement is true or false: Order and degree of a differential equation are always positive integers.(a) True(b) False
›Reveal solutionSolution
The order of a differential equation is always a positive integer, and its degree — whenever it exists — is also a positive integer, so the statement is taken as True.
- Order = the order of the highest-order derivative appearing in the equation. Since we count derivatives (dxdy, dx2d2y, …), the order is always a positive integer such as 1,2,3,… …
- CBSE 2024Set MARCH1 markMCQQ.The order and degree of the differential equation dx2d2y=dxdy+5 are respectively :(a) 2 and 1(b) 2 and 3(c) 2 and 2(d) 3 and 2
›Reveal solutionSolution
Square both sides ⇒dx2d2y=dxdy+5; order 2, degree 1.
Starting from dx2d2y=dxdy+5, square both sides to clear the radicals:
dx2d2y=dxdy+5.
…
- CBSE 2023Set ANNUAL1 markQ.Write the degree of the differential equation edxdy+dxdy=x
›Reveal solutionSolution
The derivative appears inside an exponential (transcendental) term, so the equation cannot be written as a polynomial in dxdy.
Degree is defined only when the differential equation can be expressed as a polynomial in the derivatives. Here dxdy occurs as the exponent of e (a non-polynomial/transcendental …
- CBSE 2023Set ANNUAL1 markMCQQ.Order of the differential equation (d²y/dx²)² = 1 + (dy/dx)³ is(a) 1(b) 3(c) 2(d) 4
›Reveal solutionSolution
The order of a differential equation is the order of the highest derivative that appears in it — degree (the power it's raised to) is a separate idea.
Step 1. The equation is (dx2d2y)2=1+(dxdy)3.
Step 2. The highest-order derivative present is dx2d2y, a second derivative.
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- CBSE 2023Set ANNUAL1 markMCQQ.The degree of the differential equation (dx2d2y)2+(dxdy)3=ax is 3.(a) True(b) False
›Reveal solutionSolution
The highest-order derivative is dx2d2y, raised to power 2, so the degree is 2 — the claim of 3 is False.
The degree of a differential equation is the power to which the highest-order derivative is raised, once the equation is expressed as a polynomial in its derivatives (free of radicals and fractional powers).
The equation is:
(dx2d2y)2+(dxdy)3=ax.
- The highest-order derivative is dx2d2y (order 2).
- Its power in the equation is 2. …
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