
NCERT solutions for class 12 maths Chapter 9 Differential Equations are prepared by the academic team of PW. We have prepared NCERT Solutions for all exercise of Chapter 9. Given below is step by step solutions of all questions given in the NCERT Solutions for Class 12 Maths Chapter 9 Exercise 9.3 of Differential Equations.
NCERT Solutions for Class 12 Maths Chapter 9 Miscellaneous Exercise
Solution : Given: Equation of the family of curves
….(i) Differentiating both sides of the given equation with respect to x , we get:
Hence, the required differential equation of the given curve is y'' = 0.
NCERT Solutions for Class 12 Maths Chapter 9 Exercise 9.2
Question 2.
Solution : Given: Equation of the family of curves
Differentiating both sides with respect to x , we get:
This is the required differential equation of the given curve.
NCERT Solutions for Class 12 Maths Chapter 9 Exercise 9.4
Question 3.
Solution : Given: Equation of the family of curves ….(i)
Differentiating both sides with respect to x , we get:
This is the required differential equation of the given curve.
NCERT Solutions for Class 12 Maths Chapter 9 Exercise 9.5
Question 4.
Solution : Given: Equation of the family of curves
Differentiating both sides with respect to x , we get:
This is the required differential equation of the given curve.
NCERT Solutions for Class 12 Maths Chapter 9 Exercise 9.6
Question 5.
Solution : Given: Equation of the family of curves….(i)
Differentiating both sides with respect to x , we get:
This is the required differential equation of the given curve. Question 6. Form the differential equation of the family of circles touching the y -axis at the origin. Solution : The centre of the circle touching the y -axis at origin lies on the x -axis. Let ( a , 0) be the centre of the circle. Since it touches the y -axis at origin, its radius is a . Now, the equation of the circle with centre ( a , 0) and radius ( a) is
This is the required differential equation.
Differentiating equation (1) with respect to x , we get: 2x = 4ay' Dividing equation (2) by equation (1), we get:
This is the required differential equation. Question 8. Form the differential equation of family of ellipse having foci on y -axis and centre at the origin. Solution : The equation of the family of ellipses having foci on the y -axis and the centre at origin is as follows:
This is the required differential equation. Question 9. Form the differential equation of the family of hyperbolas having foci on x -axis and centre at the origin. Solution : The equation of the family of hyperbolas with the centre at origin and foci along the x -axis is: ….(i)
This is the required differential equation. Question 10. Form the differential equation of the family of circles having centres on y -axis and radius 3 units. Solution : Let the centre of the circle on y -axis be (0, b ). The differential equation of the family of circles with centre at (0, b ) and radius 3 is as follows:
This is the required differential equation. Question 11. Which of the following differential equation has as the general solution:
Solution : Given:
….(i) Differentiating with respect to x , we get:
This is the required differential equation of the given equation of curve. Hence, the correct answer is B. Question 12. Which of the following differential equations has y = x as one of its particular solutions:
Solution : The given equation of curve is y = x . Differentiating with respect to x , we get: dy/dx = 1 ...(1) Again, differentiating with respect to x , we get: d 2 y/dx 2 = 0 ....(2) Now, on substituting the values of y , d 2 y/dx2 and dy/dx from equation (1) and (2) in each of the given alternatives, we find that only the differential equation given in alternative C is correct.
Therefore, option (C) is correct.
