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NCERT solutions for Mathematics [English] Class 12 chapter 9 - Differential Equations [Latest edition]

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NCERT solutions for Mathematics [English] Class 12 chapter 9 - Differential Equations - Shaalaa.com
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Solutions for Chapter 9: Differential Equations

Below listed, you can find solutions for Chapter 9 of CBSE, Karnataka Board PUC NCERT for Mathematics [English] Class 12.


EXERCISE 9.1EXERCISE 9.2EXERCISE 9.3EXERCISE 9.4EXERCISE 9.5Miscellaneous Exercise
EXERCISE 9.1 [Pages 303 - 304]

NCERT solutions for Mathematics [English] Class 12 9 Differential Equations EXERCISE 9.1 [Pages 303 - 304]

EXERCISE 9.1 | Q 1. | Page 303

Determine the order and degree (if defined) of the differential equation:

`(d^4y)/(dx^4) + sin(y^("')) = 0`

EXERCISE 9.1 | Q 2. | Page 303

Determine the order and degree (if defined) of the differential equation:

y' + 5y = 0

EXERCISE 9.1 | Q 3. | Page 303

Determine the order and degree (if defined) of the differential equation:

`((ds)/(dt))^4 + 3s  (d^2s)/(dt^2) = 0`

EXERCISE 9.1 | Q 4. | Page 303

Determine the order and degree (if defined) of the differential equation:

`(d^2y)/(dx^2)^2 + cos(dy/dx) = 0`

EXERCISE 9.1 | Q 5. | Page 303

Determine the order and degree (if defined) of the differential equation:

`(d^2y)/(dx^2)` = cos 3x + sin 3x

EXERCISE 9.1 | Q 6. | Page 303

Determine the order and degree (if defined) of the differential equation:

( y′′′) + (y″)3 + (y′)4 + y5 = 0

EXERCISE 9.1 | Q 7. | Page 303

Determine the order and degree (if defined) of the differential equation:

y′′′ + 2y″ + y′ = 0

EXERCISE 9.1 | Q 8. | Page 304

Determine the order and degree (if defined) of the differential equation:

y′ + y = ex

EXERCISE 9.1 | Q 9. | Page 304

Determine the order and degree (if defined) of the differential equation:

y″ + (y′)2 + 2y = 0

EXERCISE 9.1 | Q 10. | Page 304

Determine the order and degree (if defined) of the differential equation:

y″ + 2y′ + sin y = 0

EXERCISE 9.1 | Q 11. | Page 304

The degree of the differential equation `((d^2y)/(dx^2))^3 + ((dy)/(dx))^2 + sin ((dy)/(dx)) + 1 = 0` is ______.

  • 3

  • 2

  • 1

  • Not Defined

EXERCISE 9.1 | Q 12. | Page 304

The order of the differential equation `2x^2 (d^2y)/(dx^2) - 3 (dy)/(dx) + y = 0` is ______.

  • 2

  • 1

  • 0

  • Not Defined

EXERCISE 9.2 [Page 306]

NCERT solutions for Mathematics [English] Class 12 9 Differential Equations EXERCISE 9.2 [Page 306]

EXERCISE 9.2 | Q 1. | Page 306

Verify that the given function (explicit or implicit) is a solution of the corresponding differential equation:

y = ex + 1  :  y″ – y′ = 0

EXERCISE 9.2 | Q 2. | Page 306

Verify that the given function (explicit or implicit) is a solution of the corresponding differential equation:

y = x2 + 2x + C  :  y′ – 2x – 2 = 0

EXERCISE 9.2 | Q 3. | Page 306

Verify that the given function (explicit or implicit) is a solution of the corresponding differential equation:

y = cos x + C : y′ + sin x = 0

EXERCISE 9.2 | Q 4. | Page 306

Verify that the given function (explicit or implicit) is a solution of the corresponding differential equation:

`y sqrt(1 + x^2) : y' = (xy)/(1+x^2)`

EXERCISE 9.2 | Q 5. | Page 306

Verify that the given function (explicit or implicit) is a solution of the corresponding differential equation:

y = Ax : xy′ = y (x ≠ 0)

EXERCISE 9.2 | Q 6. | Page 306

Verify that the given function (explicit or implicit) is a solution of the corresponding differential equation:

y = x sin x : xy' = `y + x  sqrt (x^2 - y^2)`  (x ≠ 0 and x > y or x < -y)

EXERCISE 9.2 | Q 7. | Page 306

Verify that the given function (explicit or implicit) is a solution of the corresponding differential equation:

xy = log y + C :  `y' = (y^2)/(1 - xy) (xy != 1)`

EXERCISE 9.2 | Q 8. | Page 306

Verify that the given function (explicit or implicit) is a solution of the corresponding differential equation:

y – cos y = x :  (y sin y + cos y + x) y′ = y

EXERCISE 9.2 | Q 9. | Page 306

Verify that the given function (explicit or implicit) is a solution of the corresponding differential equation:

x + y = tan–1y   :   y2 y′ + y2 + 1 = 0

EXERCISE 9.2 | Q 10. | Page 306

Verify that the given function (explicit or implicit) is a solution of the corresponding differential equation:

`y = sqrt(a^2 - x^2 )  x in (-a,a) : x + y  dy/dx = 0(y != 0)`

EXERCISE 9.2 | Q 11. | Page 306

The number of arbitrary constants in the general solution of a differential equation of fourth order are ______.

  • 0

  • 2

  • 3

  • 4

EXERCISE 9.2 | Q 12. | Page 306

The number of arbitrary constants in the particular solution of a differential equation of third order are ______.

  • 3

  • 2

  • 1

  • 0

EXERCISE 9.3 [Pages 310 - 312]

NCERT solutions for Mathematics [English] Class 12 9 Differential Equations EXERCISE 9.3 [Pages 310 - 312]

EXERCISE 9.3 | Q 1. | Page 310

For the differential equation, find the general solution:

`dy/dx = (1 - cos x)/(1+cos x)`

EXERCISE 9.3 | Q 2. | Page 310

For the differential equation, find the general solution:

`dy/dx = sqrt(4-y^2)      (-2 < y < 2)`

EXERCISE 9.3 | Q 3. | Page 311

For the differential equation, find the general solution:

`dy/dx + y = 1(y != 1)`

EXERCISE 9.3 | Q 4. | Page 311

For the differential equation, find the general solution:

sec2 x tan y dx + sec2 y tan x dy = 0

EXERCISE 9.3 | Q 5. | Page 311

For the differential equation, find the general solution:

(ex + e–x) dy – (ex – e–x) dx = 0

EXERCISE 9.3 | Q 6. | Page 311

For the differential equation, find the general solution:

`dy/dx = (1+x^2)(1+y^2)`

EXERCISE 9.3 | Q 7. | Page 311

For the differential equation, find the general solution:

y log y dx - x dy = 0

EXERCISE 9.3 | Q 8. | Page 311

For the differential equation, find the general solution:

`x^5  dy/dx = - y^5`

EXERCISE 9.3 | Q 9. | Page 311

For the differential equation, find the general solution:

`dy/dx = sin^(-1) x`

EXERCISE 9.3 | Q 10. | Page 311

For the differential equation, find the general solution:

ex tan y dx + (1 – ex) sec2 y dy = 0

EXERCISE 9.3 | Q 11. | Page 311

For the differential equation find a particular solution satisfying the given condition:

`(x^3 + x^2 + x + 1) dy/dx = 2x^2 + x; y = 1` When x = 0

EXERCISE 9.3 | Q 12. | Page 311

For the differential equation find a particular solution satisfying the given condition:

`x(x^2 - 1) dy/dx = 1` , y = 0  when x = 2

EXERCISE 9.3 | Q 13. | Page 311

For the differential equation find a particular solution satisfying the given condition:

`cos (dx/dy) = a(a in R); y = 1` when x = 0

EXERCISE 9.3 | Q 14. | Page 311

For the differential equation find a particular solution satisfying the given condition:

`dy/dx` = y tan x; y = 1 when x = 0

EXERCISE 9.3 | Q 15. | Page 311

Find the equation of a curve passing through the point (0, 0) and whose differential equation is y′ = e x sin x.

EXERCISE 9.3 | Q 16. | Page 311

For the differential equation `xy(dy)/(dx) = (x + 2)(y + 2)`  find the solution curve passing through the point (1, –1).

EXERCISE 9.3 | Q 17. | Page 311

Find the equation of a curve passing through the point (0, -2) given that at any point (x, y) on the curve, the product of the slope of its tangent and y-coordinate of the point is equal to the x-coordinate of the point.

EXERCISE 9.3 | Q 18. | Page 311

At any point (x, y) of a curve, the slope of the tangent is twice the slope of the line segment joining the point of contact to the point (- 4, -3). Find the equation of the curve given that it passes through (-2, 1).

EXERCISE 9.3 | Q 19. | Page 311

The volume of spherical balloon being inflated changes at a constant rate. If initially its radius is 3 units and after 3 seconds it is 6 units. Find the radius of balloon after t seconds.

EXERCISE 9.3 | Q 20. | Page 312

In a bank, principal increases continuously at the rate of r% per year. Find the value of r if Rs 100 doubles itself in 10 years (log­e 2 = 0.6931).

EXERCISE 9.3 | Q 21. | Page 312

In a bank, principal increases continuously at the rate of 5% per year. An amount of Rs 1000 is deposited with this bank, how much will it worth after 10 years (e0.5 = 1.648).

EXERCISE 9.3 | Q 22. | Page 312

In a culture, the bacteria count is 1,00,000. The number is increased by 10% in 2 hours. In how many hours will the count reach 2,00,000, if the rate of growth of bacteria is proportional to the number present?

EXERCISE 9.3 | Q 23. | Page 312

The general solution of the differential equation `dy/dx = e^(x+y)` is ______.

  • ex + e-y = C

  • ex + ey = C

  • e-x + ey = C

  • e-x + e-y = C

EXERCISE 9.4 [Pages 321 - 322]

NCERT solutions for Mathematics [English] Class 12 9 Differential Equations EXERCISE 9.4 [Pages 321 - 322]

EXERCISE 9.4 | Q 1. | Page 321

Show that the given differential equation is homogeneous and solve them.

(x2 + xy) dy = (x2 + y2) dx

EXERCISE 9.4 | Q 2. | Page 321

Show that the given differential equation is homogeneous and solve them.

`y' = (x + y)/x`

EXERCISE 9.4 | Q 3. | Page 321

Show that the given differential equation is homogeneous and solve them.

(x – y) dy – (x + y) dx = 0

EXERCISE 9.4 | Q 4. | Page 321

Show that the given differential equation is homogeneous and solve them.

(x2 – y2) dx + 2xy dy = 0

EXERCISE 9.4 | Q 5. | Page 321

Show that the given differential equation is homogeneous and solve them.

`x^2 dy/dx = x^2 - 2y^2 + xy`

EXERCISE 9.4 | Q 6. | Page 321

Show that the given differential equation is homogeneous and solve them.

`x  dy - y  dx =  sqrt(x^2 + y^2)   dx`

EXERCISE 9.4 | Q 7. | Page 321

Show that the given differential equation is homogeneous and solve them.

`{xcos(y/x) + ysin(y/x)}ydx = {ysin (y/x) -  xcos(y/x)}xdy`

EXERCISE 9.4 | Q 8. | Page 321

Show that the given differential equation is homogeneous and solve them.

`x dy/dx - y +  x sin (y/x) = 0`

EXERCISE 9.4 | Q 9. | Page 321

Show that the given differential equation is homogeneous and solve them.

`y  dx + x log(y/x)dy - 2x  dy = 0`

EXERCISE 9.4 | Q 10. | Page 321

Show that the given differential equation is homogeneous and solve them.

`(1+e^(x/y))dx + e^(x/y) (1 - x/y)dy = 0`

EXERCISE 9.4 | Q 11. | Page 321

For the differential equation find a particular solution satisfying the given condition:

(x + y) dy + (x – y) dx = 0; y = 1 when x = 1

EXERCISE 9.4 | Q 12. | Page 321

For the differential equation find a particular solution satisfying the given condition:

x2 dy + (xy + y2) dx = 0; y = 1 when x = 1

EXERCISE 9.4 | Q 13. | Page 321

For the differential equation find a particular solution satisfying the given condition:

`[xsin^2(y/x - y)] dx + x  dy = 0; y = pi/4 "when"  x = 1`

EXERCISE 9.4 | Q 14. | Page 321

For the differential equation find a particular solution satisfying the given condition:

`dy/dx -  y/x + cosec (y/x) = 0; y = 0` when x = 1

EXERCISE 9.4 | Q 15. | Page 321

For the differential equation find a particular solution satisfying the given condition:

`2xy + y^2 - 2x^2  dy/dx = 0; y = 2`   when x  = 1

EXERCISE 9.4 | Q 16. | Page 321

A homogeneous differential equation of the from `dx/dy = h (x/y)` can be solved by making the substitution.

  • y = vx

  • v = yx

  • x = vy

  • x = v

EXERCISE 9.4 | Q 17. | Page 322

Which of the following is a homogeneous differential equation?

  • (4x + 6y + 5) dy – (3y + 2x + 4) dx = 0

  • (xy) dx – (x3 + y3) dy = 0

  • (x3 + 2y2) dx + 2xy dy = 0

  • y2 dx + (x2 – xy – y2) dy = 0

EXERCISE 9.5 [Pages 328 - 329]

NCERT solutions for Mathematics [English] Class 12 9 Differential Equations EXERCISE 9.5 [Pages 328 - 329]

EXERCISE 9.5 | Q 1. | Page 328

For the differential equation, find the general solution:

`dy/dx  + 2y = sin x`

EXERCISE 9.5 | Q 2. | Page 328

For the differential equation, find the general solution:

`dy/dx + 3y = e^(-2x)`

EXERCISE 9.5 | Q 3. | Page 328

For the differential equation, find the general solution:

`dy/dx + y/x = x^2`

EXERCISE 9.5 | Q 4. | Page 328

For the differential equation, find the general solution:

`dy/dx + (sec x) y = tan x (0 <= x < pi/2)`

EXERCISE 9.5 | Q 5. | Page 328

For the differential equation, find the general solution:

`cos^2 x dy/dx + y = tan x(0 <= x < pi/2)`

EXERCISE 9.5 | Q 6. | Page 328

For the differential equation, find the general solution:

`x dy/dx +  2y= x^2 log x`

EXERCISE 9.5 | Q 7. | Page 328

For the differential equation, find the general solution:

`x log x dy/dx + y=    2/x log x`

EXERCISE 9.5 | Q 8. | Page 328

For the differential equation, find the general solution:

(1 + x2) dy + 2xy dx = cot x dx (x ≠ 0)

EXERCISE 9.5 | Q 9. | Page 329

For the differential equation, find the general solution:

`x dy/dx + y - x + xy cot x = 0(x != 0)`

EXERCISE 9.5 | Q 10. | Page 329

For the differential equation, find the general solution:

`(x + y) dy/dx = 1`

EXERCISE 9.5 | Q 11. | Page 329

For the differential equation, find the general solution:

y dx + (x – y2) dy = 0

EXERCISE 9.5 | Q 12. | Page 329

For the differential equation, find the general solution:

`(x + 3y^2) dy/dx = y(y > 0)`

EXERCISE 9.5 | Q 13. | Page 329

For the differential equation given, find a particular solution satisfying the given condition:

`dy/dx + 2y tan x = sin x; y = 0 " when x " = pi/3`

EXERCISE 9.5 | Q 14. | Page 329

For the differential equation given, find a particular solution satisfying the given condition:

`(1 + x^2)dy/dx + 2xy = 1/(1 + x^2); y = 0`  when x = 1

EXERCISE 9.5 | Q 15. | Page 329

For the differential equation given, find a particular solution satisfying the given condition:

`dy/dx - 3ycotx = sin 2x; y = 2`  when `x = pi/2`

EXERCISE 9.5 | Q 16. | Page 329

Find the equation of the curve passing through the origin given that the slope of the tangent to the curve at any point (x, y) is equal to the sum of the coordinates of the point.

EXERCISE 9.5 | Q 17. | Page 329

Find the equation of a curve passing through the point (0, 2) given that the sum of the coordinates of any point on the curve exceeds the magnitude of the slope of the tangent to the curve at that point by 5.

EXERCISE 9.5 | Q 18. | Page 329

The Integrating Factor of the differential equation `dy/dx - y = 2x^2` is ______.

  • e-x

  • e-y

  • `1/x`

  • x

EXERCISE 9.5 | Q 19. | Page 329

The integrating factor of the differential equation.

`(1 - y^2) dx/dy + yx = ay(-1 < y < 1)` is ______.

  • `1/(y^2 - 1)`

  • `1/sqrt(y^2 - 1)`

  • `1/(1 - y^2)`

  • `1/sqrt(1 - y^2)`

Miscellaneous Exercise [Pages 334 - 335]

NCERT solutions for Mathematics [English] Class 12 9 Differential Equations Miscellaneous Exercise [Pages 334 - 335]

Miscellaneous Exercise | Q 1. (i) | Page 334

For the differential equation given below, indicate its order and degree (if defined).

`(d^2y)/dx^2 + 5x(dy/dx)^2 - 6y = log x`

Miscellaneous Exercise | Q 1. (ii) | Page 334

For the differential equation given below, indicate its order and degree (if defined).

`((dy)/(dx))^3 -4(dy/dx)^2 + 7y = sin x`

Miscellaneous Exercise | Q 1. (iii) | Page 334

For the differential equation given below, indicate its order and degree (if defined).

`(d^4y)/dx^4 - sin ((d^3y)/(dx^3)) = 0`

Miscellaneous Exercise | Q 2. (i) | Page 334

For the given below, verify that the given function (implicit or explicit) is a solution to the corresponding differential equation.

xy = a ex + b e-x + x2 : `x (d^2y)/(dx^2) + 2 dy/dx - xy + x^2 - 2 = 0`

Miscellaneous Exercise | Q 2. (ii) | Page 334

For the given below, verify that the given function (implicit or explicit) is a solution to the corresponding differential equation.

`y = e^x (acos x + b sin x)  :  (d^2y)/(dx^2) - 2 dy/dx + 2y = 0`

Miscellaneous Exercise | Q 2. (iii) | Page 334

For the given below, verify that the given function (implicit or explicit) is a solution to the corresponding differential equation.

`y = xsin 3x   :   (d^2y)/(dx^2) + 9y - 6 cos 3x = 0`

Miscellaneous Exercise | Q 2. (iv) | Page 334

For the given below, verify that the given function (implicit or explicit) is a solution to the corresponding differential equation.

`x^2 = 2y^2 log y : (x^2  + y^2) dy/dx - xy = 0`

Miscellaneous Exercise | Q 3. | Page 334

Prove that x2 – y2 = c (x2 + y2)2 is the general solution of differential equation  (x3 – 3x y2) dx = (y3 – 3x2y) dy, where c is a parameter.

Miscellaneous Exercise | Q 4. | Page 334

Find the general solution of the differential equation `dy/dx + sqrt((1-y^2)/(1-x^2)) = 0.`

Miscellaneous Exercise | Q 5. | Page 334

Show that the general solution of the differential equation  `dy/dx + (y^2 + y +1)/(x^2 + x + 1) = 0` is given by (x + y + 1) = A (1 - x - y - 2xy), where A is parameter.

Miscellaneous Exercise | Q 6. | Page 334

Find the equation of the curve passing through the point `(0,pi/4)`, whose differential equation is sin x cos y dx + cos x sin y dy = 0.

Miscellaneous Exercise | Q 7. | Page 334

Find the particular solution of the differential equation (1 + e2x) dy + (1 + y2) ex dx = 0, given that y = 1 when x = 0.

Miscellaneous Exercise | Q 8. | Page 334

Solve the differential equation  `ye^(x/y) dx = (xe^(x/y) + y^2)dy, (y != 0)`

Miscellaneous Exercise | Q 9. | Page 335

Find a particular solution of the differential equation (x - y) (dx + dy) = dx - dy, given that y = -1, when x = 0. (Hint: put x - y = t)

Miscellaneous Exercise | Q 10. | Page 335

Solve the differential equation `[e^(-2sqrtx)/sqrtx - y/sqrtx] dx/dy = 1 (x != 0).`

Miscellaneous Exercise | Q 11. | Page 335

Find a particular solution of the differential equation `dy/dx + y cot x = 4xcosec x(x != 0)`, given that y = 0 when `x = pi/2.`

Miscellaneous Exercise | Q 12. | Page 335

Find a particular solution of the differential equation`(x + 1) dy/dx = 2e^(-y) - 1`, given that y = 0 when x = 0.

Miscellaneous Exercise | Q 13. | Page 335

The general solution of the differential equation `(y dx - x dy)/y = 0` is ______.

  • xy = C

  • x = Cy2

  • y = Cx

  • y = Cx2

Miscellaneous Exercise | Q 14. | Page 335

The general solution of a differential equation of the type  `dx/dy + P_1 x = Q_1` is ______.

  • `y e^(intP_1 dy) = int(Q_1 e^(intP_1 dy)) dy + C`

  • `y . e^(intP_1 dx) = int(Q_1 e^(intP_1 dx)) dx + C`

  • `x e^(intP_1 dy) = int(Q_1 e^(intP_1 dy)) dy + C`

  • `xe^(intP_1 dx) = int(Q_1 e^(intP_1 dx)) dx + C`

Miscellaneous Exercise | Q 15. | Page 335

The general solution of the differential equation ex dy + (y ex + 2x) dx = 0 is ______.

  • xey + x2 = C

  • xey + y2 = C

  • yex + x2 = C

  • yey + x2 = C

Solutions for 9: Differential Equations

EXERCISE 9.1EXERCISE 9.2EXERCISE 9.3EXERCISE 9.4EXERCISE 9.5Miscellaneous Exercise
NCERT solutions for Mathematics [English] Class 12 chapter 9 - Differential Equations - Shaalaa.com

NCERT solutions for Mathematics [English] Class 12 chapter 9 - Differential Equations

Shaalaa.com has the CBSE, Karnataka Board PUC Mathematics Mathematics [English] Class 12 CBSE, Karnataka Board PUC solutions in a manner that help students grasp basic concepts better and faster. The detailed, step-by-step solutions will help you understand the concepts better and clarify any confusion. NCERT solutions for Mathematics Mathematics [English] Class 12 CBSE, Karnataka Board PUC 9 (Differential Equations) include all questions with answers and detailed explanations. This will clear students' doubts about questions and improve their application skills while preparing for board exams.

Further, we at Shaalaa.com provide such solutions so students can prepare for written exams. NCERT textbook solutions can be a core help for self-study and provide excellent self-help guidance for students.

Concepts covered in Mathematics [English] Class 12 chapter 9 Differential Equations are Procedure to Form a Differential Equation that Will Represent a Given Family of Curves, Linear Differential Equations, Solutions of Linear Differential Equation, Homogeneous Differential Equations, Differential Equations with Variables Separable Method, Formation of a Differential Equation Whose General Solution is Given, General and Particular Solutions of a Differential Equation, Order and Degree of a Differential Equation, Differential Equations, Procedure to Form a Differential Equation that Will Represent a Given Family of Curves, Linear Differential Equations, Solutions of Linear Differential Equation, Homogeneous Differential Equations, Differential Equations with Variables Separable Method, Formation of a Differential Equation Whose General Solution is Given, General and Particular Solutions of a Differential Equation, Order and Degree of a Differential Equation, Differential Equations.

Using NCERT Mathematics [English] Class 12 solutions Differential Equations exercise by students is an easy way to prepare for the exams, as they involve solutions arranged chapter-wise and also page-wise. The questions involved in NCERT Solutions are essential questions that can be asked in the final exam. Maximum CBSE, Karnataka Board PUC Mathematics [English] Class 12 students prefer NCERT Textbook Solutions to score more in exams.

Get the free view of Chapter 9, Differential Equations Mathematics [English] Class 12 additional questions for Mathematics Mathematics [English] Class 12 CBSE, Karnataka Board PUC, and you can use Shaalaa.com to keep it handy for your exam preparation.

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