

NCERT Solutions for Class 12 Maths Chapter 9 Exercise 9.1 Differential Equations is prepared by the academic team of Physics Wallah. We have prepared NCERT Solutions for all exercise of Chapter 9. Given below is step by step solutions to all questions given in the NCERT Solutions for Class 12 Maths Chapter 9 Exercise 9.1 Differential Equations.
NCERT Solutions for Class 12 Maths Chapter 9 Miscellaneous Exercise
Solve The Following Questions of NCERT Solutions for Class 12 Maths Chapter 9 Exercise 9.1
Determine order and degree (if defined) of differential equations given in Questions 1 to 10: Question 1.
Solution :
Given:
The highest order derivative present in the differential equation is y'''' and its order is 4.
The given differential equation is not a polynomial equation in its derivatives. Hence, its degree is not defined.
NCERT Solutions for Class 12 Maths Chapter 9 Exercise 9.2
Question 2. y' + 5y = 0 Solution : The given differential equation is: y' + 5y = 0 The highest order derivative present in the differential equation is y'. Therefore, its order is one. It is a polynomial equation in y'. The highest power raised to y'is 1. Hence, its degree is one.NCERT Solutions for Class 12 Maths Chapter 9 Exercise 9.3
Question 3.
Solution :
Given:
The highest order derivative present in the given differential equation is d
2
s/dt
2
Therefore, its order is two.
It is a polynomial equation in d
2
s/dt
2
and ds/dt. The power raised to d
2
s/dt
2
is 1.
Hence, its degree is one.
NCERT Solutions for Class 12 Maths Chapter 9 Exercise 9.4
Question 4.
Solution :
Given:
The highest order derivative present in the given differential equation is d
2
y/dx
2
Therefore, its order is 2.
The given differential equation is not a polynomial equation in its derivatives. Hence, its degree is not defined.
NCERT Solutions for Class 12 Maths Chapter 9 Exercise 9.5
Question 5.
Solution :
Given:
The highest order derivative present in the differential equation is d
2
y/dx
2
and its order is 2.
The given differential equation is a polynomial equation in derivatives and the highest power raised to highest order d
2
y/dx
2
is one, so its degree is 1.
Hence, order is 2 and degree is 1.
NCERT Solutions for Class 12 Maths Chapter 9 Exercise 9.6
Question 6.
Solution :
Given:
The highest order derivative present in the differential equation is y'''. Therefore, its order is three.
The given differential equation is a polynomial equation in y''', y'', and y'.
The highest power raised to y''' is 2. Hence, its degree is 2.
Question
7.
y''' + 2y'' + y' = 0
Solution :
Given: y''' + 2y'' + y' = 0
The highest order derivative present in the differential equation is y'''. Therefore, its order is three.
It is a polynomial equation in y''', y'' and y'. The highest power raised to y'''is 1. Hence, its degree is 1.
Question
8.
y′ + y = e
x
Solution :
Given: y′ + y = e
x
⇒ y′ + y - e
x
= 0
The highest order derivative present in the differential equation is y'. Therefore, its order is one.
The given differential equation is a polynomial equation in y' and the highest power raised to y' is one. Hence, its degree is one.
Question
9.
y'′ + (y')
2
+ 2y = 0
Solution :
Given: y'′ + (y')
2
+ 2y = 0
The highest order derivative present in the differential equation is y''. Therefore, its order is two.
The given differential equation is a polynomial equation in y''and y' and the highest power raised to y'' is one.
Hence, its degree is one.
Question
10.
y'′ + 2y' + sin y = 0
Solution :
Given: y'′ + 2y' + sin y = 0
The highest order derivative present in the differential equation is y''. Therefore, its order is two.
This is a polynomial equation in y''. and y'.and the highest power raised to y''. is one. Hence, its degree is one.
Question
11. The degree of the differential equation is:
(A) 3
(B) 2
(C) 1
(D) Not defined
Solution :
Given:
……….(i)
The given differential equation is not a polynomial equation in its derivatives. Therefore, its degree is not defined.
Hence, the correct answer is D.
Hence, option (D) is correct.
Question
12. The order of the differential equation is:
(A) 2
(B) 1
(C) 0
(D) Not defined
Solution :
Given:
The highest order derivative present in the differential equation is d
2
y/dx2 and its order is 2.
Therefore, option (A) is correct.
