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NCERT solutions for Mathematics Part 1 and 2 [English] Class 12 chapter 9 - Differential Equations [Latest edition]

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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 Part 1 and 2 [English] Class 12.


Exercise 9.1Exercise 9.2Exercise 9.3Exercise 9.4Exercise 9.5Exercise 9.6Exercise 9.7
Exercise 9.1 [Pages 382 - 383]

NCERT solutions for Mathematics Part 1 and 2 [English] Class 12 9 Differential Equations Exercise 9.1 [Pages 382 - 383]

1Page 382

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

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

2Page 382

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

y' + 5y = 0

3Page 382

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

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

4Page 382

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

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

5Page 382

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

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

6Page 382

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

( y′′′) + (y″)3 + (y′)4 + y5 = 0

7Page 382

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

y′′′ + 2y″ + y′ = 0

8Page 383

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

y′ + y = ex

9Page 383

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

y″ + (y′)2 + 2y = 0

10Page 383

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

y″ + 2y′ + sin y = 0

11Page 383

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

12Page 383

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 385]

NCERT solutions for Mathematics Part 1 and 2 [English] Class 12 9 Differential Equations Exercise 9.2 [Page 385]

1Page 385

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

y = ex + 1  :  y″ – y′ = 0

2Page 385

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

y = x2 + 2x + C  :  y′ – 2x – 2 = 0

3Page 385

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

y = cos x + C : y′ + sin x = 0

4Page 385

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)`

5Page 385

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

y = Ax : xy′ = y (x ≠ 0)

6Page 385

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)

7Page 385

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)`

8Page 385

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

9Page 385

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

10Page 385

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)`

11Page 385

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

  • 0

  • 2

  • 3

  • 4

12Page 385

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

  • 3

  • 2

  • 1

  • 0

Exercise 9.3 [Page 391]

NCERT solutions for Mathematics Part 1 and 2 [English] Class 12 9 Differential Equations Exercise 9.3 [Page 391]

1Page 391

Form a differential equation representing the given family of curves by eliminating arbitrary constants a and b.

`x/a + y/b = 1`

2Page 391

Form a differential equation representing the given family of curves by eliminating arbitrary constants a and b.

y2 = a (b2 – x2)

3Page 391

Form a differential equation representing the given family of curves by eliminating arbitrary constants a and b.

y = a e3x + b e– 2x

4Page 391

Form a differential equation representing the given family of curves by eliminating arbitrary constants a and b.

y = e2x (a + bx)

5Page 391

Form a differential equation representing the given family of curves by eliminating arbitrary constants a and b.

y = ex (a cos x + b sin x)

6Page 391

Form the differential equation of the family of circles touching the y-axis at the origin.

7Page 391

Form the differential equation of the family of parabolas having vertex at origin and axis along positive y-axis.

8Page 391

Form the differential equation of the family of ellipses having foci on y-axis and centre at origin.

9Page 391

Form the differential equation of the family of hyperbolas having foci on x-axis and centre at origin.

10Page 391

Form the differential equation of the family of circles having centre on y-axis and radius 3 units.

 
11Page 391

Which of the following differential equations has y = c1 ex + c2 e–x as the general solution?

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

(B) `(d^2y)/(dx^2) - y = 0`

(C) `(d^2y)/(dx^2) + 1 = 0`

(D) `(d^2y)/(dx^2)  - 1 = 0`

 

 

12Page 391

Which of the following differential equation has y = x as one of its particular solution?

A. `(d^2y)/(dx^2) - x^2 (dy)/(dx) + xy = x`

B. `(d^2y)/(dx^2) + x dy/dx + xy = x`

C. `(d^2y)/(dx^2) - x^2 dy/dx + xy = 0`

D. `(d^2y)/(dx^2) + x dy/dx + xy = 0`

 

 

 

Exercise 9.4 [Pages 395 - 397]

NCERT solutions for Mathematics Part 1 and 2 [English] Class 12 9 Differential Equations Exercise 9.4 [Pages 395 - 397]

1Page 395

For the differential equation, find the general solution:

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

2Page 395

For the differential equation, find the general solution:

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

3Page 396

For the differential equation, find the general solution:

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

4Page 396

For the differential equation, find the general solution:

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

5Page 396

For the differential equation, find the general solution:

(ex + e–x) dy – (ex – e–x) dx = 0

6Page 396

For the differential equation, find the general solution:

`dy/dx = (1+x^2)(1+y^2)`

7Page 396

For the differential equation, find the general solution:

y log y dx - x dy = 0

8Page 396

For the differential equation, find the general solution:

`x^5  dy/dx = - y^5`

9Page 396

For the differential equation, find the general solution:

`dy/dx = sin^(-1) x`

10Page 396

For the differential equation, find the general solution:

ex tan y dx + (1 – ex) sec2 y dy = 0

11Page 396

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

12Page 396

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

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

13Page 396

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

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

14Page 396

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

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

15Page 396

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

16Page 396

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

17Page 396

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.

18Page 396

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).

19Page 396

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.

20Page 397

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).

21Page 397

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).

22Page 397

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?

23Page 397

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 9.5 [Pages 406 - 407]

NCERT solutions for Mathematics Part 1 and 2 [English] Class 12 9 Differential Equations Exercise 9.5 [Pages 406 - 407]

1Page 406

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

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

2Page 406

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

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

3Page 406

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

(x – y) dy – (x + y) dx = 0

4Page 406

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

(x2 – y2) dx + 2xy dy = 0

5Page 406

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

`x^2 dy/dx = x^2 - 2y^2 + xy`

6Page 406

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

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

7Page 406

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`

8Page 406

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

`x dy/dx - y +  x sin (y/x) = 0`

9Page 406

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

`y  dx + x log(y/x)dy - 2x  dy = 0`

10Page 406

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

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

11Page 406

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

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

12Page 406

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

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

13Page 406

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`

14Page 406

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

15Page 406

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

16Page 406

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

17Page 407

Which of the following is a homogeneous differential equation?

  • (4x2 + 6y + 5) dy – (3y2 + 2x + 4) dx = 0

  • (xy) dx – (x3 + y3) dy = 0

  • (x3 + 2y2) dx + 2xy dy = 0

  • y2 dx + (x2 – xy – y2) dy = 0

Exercise 9.6 [Pages 413 - 414]

NCERT solutions for Mathematics Part 1 and 2 [English] Class 12 9 Differential Equations Exercise 9.6 [Pages 413 - 414]

1Page 413

For the differential equation, find the general solution:

`dy/dx  + 2y = sin x`

2Page 413

For the differential equation, find the general solution:

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

3Page 413

For the differential equation, find the general solution:

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

4Page 413

For the differential equation, find the general solution:

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

5Page 413

For the differential equation, find the general solution:

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

6Page 413

For the differential equation, find the general solution:

`x dy/dx +  2y= x^2 log x`

7Page 413

For the differential equation, find the general solution:

`x log x dy/dx + y=    2/x log x`

8Page 413

For the differential equation, find the general solution:

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

9Page 414

For the differential equation, find the general solution:

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

10Page 414

For the differential equation, find the general solution:

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

11Page 414

For the differential equation, find the general solution:

y dx + (x – y2) dy = 0

12Page 414

For the differential equation, find the general solution:

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

13Page 414

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`

14Page 414

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

15Page 414

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

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

16Page 414

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.

17Page 414

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.

18Page 414

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

  • e-x

  • e-y

  • `1/x`

  • x

19Page 414

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)`

Exercise 9.7 [Pages 419 - 421]

NCERT solutions for Mathematics Part 1 and 2 [English] Class 12 9 Differential Equations Exercise 9.7 [Pages 419 - 421]

1.1Page 419

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

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

1.2Page 419

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

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

1.3Page 419

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

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

2.1Page 420

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`

2.2Page 420

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`

2.3Page 420

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`

2.4Page 420

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`

3Page 420

Form the differential equation representing the family of curves given by (x – a)2 + 2y2 = a2, where a is an arbitrary constant.

4Page 420

Form the differential equation of the family of circles in the first quadrant which touch the coordinate axes.

4Page 420

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.

6Page 420

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

7Page 420

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.

8Page 420

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.

9Page 420

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

10Page 420

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

11Page 420

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)

12Page 421

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

13Page 421

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.`

14Page 421

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

15Page 421

The population of a village increases continuously at the rate proportional to the number of its inhabitants present at any time. If the population of the village was 20000 in 1999 and 25000 in the year 2004, what will be the population of the village in 2009?

16Page 421

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

  • xy = C

  • x = Cy2

  • y = Cx

  • y = Cx2

17Page 421

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`

18Page 421

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 9.5Exercise 9.6Exercise 9.7

NCERT solutions for Mathematics Part 1 and 2 [English] Class 12 chapter 9 - Differential Equations

Shaalaa.com has the CBSE, Karnataka Board PUC Mathematics Mathematics Part 1 and 2 [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 Part 1 and 2 [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 Part 1 and 2 [English] Class 12 chapter 9 Differential Equations are Basic Concepts of Differential Equations, Order and Degree of a Differential Equation, General and Particular Solutions of a Differential Equation, Methods of Solving Differential Equations> Homogeneous Differential Equations, Methods of Solving Differential Equations> Variable Separable Differential Equations, Methods of Solving Differential Equations>Linear Differential Equations, Overview of Differential Equations, Basic Concepts of Differential Equations, Order and Degree of a Differential Equation, General and Particular Solutions of a Differential Equation, Methods of Solving Differential Equations> Homogeneous Differential Equations, Methods of Solving Differential Equations> Variable Separable Differential Equations, Methods of Solving Differential Equations>Linear Differential Equations, Overview of Differential Equations.

Using NCERT Mathematics Part 1 and 2 [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 Part 1 and 2 [English] Class 12 students prefer NCERT Textbook Solutions to score more in exams.

Get the free view of Chapter 9, Differential Equations Mathematics Part 1 and 2 [English] Class 12 additional questions for Mathematics Mathematics Part 1 and 2 [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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