

Solve The Following Questions of NCERT Solutions for Class 12 Maths Chapter 9 Exercise 9.6:
In each of the following differential equations given in each Questions 1 to 4, find the general solution: Question 1.
Solution :
Given: Differential equation
This is the required general solution of the given differential equation.
Question
2.
Solution :
Question
3.
Solution :
Given: Differential equation
Question
4.
Solution :
Given: Differential equation
For each of the following differential equations given in Question 5 to 8, find the general solution:
Question
5.
Solution :
The given differential equation is:
Question
6.
Solution :
Given: Differential equation
Question
7.
Solution :
Given: Differential equation
Question
8.
Solution :
Given: Differential equation
For each of the following differential equations given in Question 9 to 12, find the general solution:
Question
9.
Solution :
Given: Differential equation
Question
10.
Solution :
Given: Differential equation
Question
11.
Solution :
Given: Differential equation
Question
12.
Solution :
Given: Differential equation
For each of the differential equations given in Questions 13 to 15, find a particular solution satisfying the given condition:
Question
13.
Solution :
Given: Differential equation
This is a linear equation of the form:
Hence, the required solution of the given differential equation is y = cos x - 2 cos
2
x.
Question
14.
Solution :
Given: Differential equation
This is the required general solution of the given differential equation.
Question
15.
Solution :
Given: Differential equation
This is the required particular solution of the given differential equation.
Question
16. 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 coordinates of that point.
Solution :
Let
F
(
x
,
y
) be the curve passing through the origin.
At point (
x
,
y
), the slope of the curve will be dy/dx.
According to the given information:
The curve passes through the origin.
Therefore, equation (2) becomes:
1 = C
⇒ C = 1
Substituting C = 1 in equation (2), we get:
x + y + 1 = e
x
Hence, the required equation of curve passing through the origin is x + y + 1 = e
x
.
Question
17. Find the equation of the 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 tangents to the curve at that point by 5.
Solution :
Let
F
(
x
,
y
) be the curve and let (
x
,
y
) be a point on the curve. The slope of the tangent to the curve at (
x
,
y
) is dy/dx.
According to the given information:
The curve passes through point (0, 2).
Therefore, equation (2) becomes:
0 + 2 – 4 = C
e
0
⇒ – 2 = C
⇒ C = – 2
Substituting C = –2 in equation (2), we get:
x + y -4 = - 2e
x
⇒y = 4 - x - 2e
x
This is the required equation of the curve.
Question
18. Choose the correct answer:
The integrating factor of the differential equation is:
(A)
e
–
x
(B)
e
–
y
(C) 1/x
(D)
x
Solution :
Given: Differential equation
Therefore, option (C) is correct.
Question
19. Choose the correct answer:
The integrating factor of the differential equation
Solution :
Given: Differential equation
Therefore, option (D) is correct.
