Plus Two Maths Chapter Wise Previous Questions Chapter 9 Differential Equations

Plus Two Maths Chapter Wise Previous Questions Chapter 9 Differential Equations are part of Plus Two Maths Chapter Wise Previous Year Questions and Answers. Here we have given Plus Two Maths Chapter Wise Previous Chapter 9 Differential Equations.

Kerala Plus Two Maths Chapter Wise Previous Questions Chapter 9 Differential Equations

Plus Two Maths Differential Equations 3 Marks Important Questions

Question 1.
Form a differential equation of the family of circles having a centre on y-axis and radius 3 units. (May -2013)
Answer:
The equation of the circle passing through the point (O,k)and radius 3 is of the form
Plus Two Maths Chapter Wise Previous Questions Chapter 9 Differential Equations 1

Question 2.
Consider the Differential equation
\(\frac{d^{2} y}{d x^{2}}+y=0\)
(i) Write the order and degree.
(ii) Verify that y = a cos x + b sin x where a,b ∈ R is a solution of the given DE. (March – 2014)
Answer:
(i) Order = 2; Degree = I
(ii) Given; y = acosx + bsin x
y1 = – asin x + bcos x
y2 = – acos x – bsin x
We have; y2 = – (a cos x + b sin x)
⇒ y2 = -y ⇒ y2 + y = 0

Plus Two Maths Differential Equations 4 Marks Important Questions

Question 1.
If cosx\(\frac{d y}{d x}\) + y sin x = tan2 x is a DE then
(i) Find its order and degree.
(ii) Find its general solution. (May -2010)
Answer:
Plus Two Maths Chapter Wise Previous Questions Chapter 9 Differential Equations 2

Question 2.
(i) Write the order and degree of the DE
\(\left[\frac{d y}{d x}\right]^{2}+\frac{d y}{d x}-\sin ^{2} y=0\)
(ii) Solve the \(\frac{d y}{d x}+2 y \tan x=\sin x\) (May-2011)
Answer:
Plus Two Maths Chapter Wise Previous Questions Chapter 9 Differential Equations 3

Question 3.
(i) The general solution of the DE \(\frac{d y}{d x}=e^{x-y} \text { is }\)
(a) ey + ex = c
(b) ey ex = c
(c) e-y + e-x = c
(d) e-y – ex = c
(ii) Solve the DE \(\frac{d y}{d x}=\frac{2 x y}{1+x^{2}}+x^{2}+2\) (March – 2013)
Answer:
Plus Two Maths Chapter Wise Previous Questions Chapter 9 Differential Equations 4

Question 4.
(a) Consider the family of all circles having their centre at the point (1,2). Write the equation of the family. Write the corresponding differential equation.
(b) Write the integrating factor of the differential equation
\(\cos x \frac{d y}{d x}+y=\sin x, \quad 0 \leq x<\frac{\pi}{2}\) (March – 2015)
Answer:
(a) The equation of the circle ¡s
Plus Two Maths Chapter Wise Previous Questions Chapter 9 Differential Equations 5

Question 5.
(a) Write the order and degree of the differential equations.
\(x y\left(\frac{d^{2} y}{d x^{2}}\right)^{2}+x\left(\frac{d y}{d x}\right)^{3}-y \frac{d y}{d x}=0\)

(b) Find the general solution of the differential equation ylog ydx – xdy = 0
(c) Find the integrating factor of the differential equation \(x \frac{d y}{d x}-y=2 x^{2}\) (May -2015)
Answer:
Plus Two Maths Chapter Wise Previous Questions Chapter 9 Differential Equations 6
Plus Two Maths Chapter Wise Previous Questions Chapter 9 Differential Equations 7

Question 6.
(a) y = a cosx +b sin x is the solution of the differential equation
Plus Two Maths Chapter Wise Previous Questions Chapter 9 Differential Equations 8
(b) Find the solution of the differential equation \(x \frac{d y}{d x}+2 y=x^{2}, \quad(x \neq 0)\) given that y = 0 when x=1. (March – 2016)
Answer:
Plus Two Maths Chapter Wise Previous Questions Chapter 9 Differential Equations 9

Plus Two Maths Differential Equations 6 Marks Important Questions

Question 1.
(i) Form the DE corresponding to the Function y = aex + be2x
(ii) State the order and degree of the above DE.
(iii) Solve \(x \frac{d y}{d x}=x+y\) (March – 2009)
Answer:
Plus Two Maths Chapter Wise Previous Questions Chapter 9 Differential Equations 10
Plus Two Maths Chapter Wise Previous Questions Chapter 9 Differential Equations 11

Question 2.
(i) Form the DE corresponding to the function Xy = C2
(ii) Consider the DE (x2 + y2 ) dx = 2xydy
(a) Write the DE in the ton \(\frac{d y}{d x}=g\left[\frac{y}{x}\right]\)
(b) Solve the DE completely (May -2009, May -2013)
Answer:
Plus Two Maths Chapter Wise Previous Questions Chapter 9 Differential Equations 12

Question 3.
(i) Equation of a circle touching the y-axis at origin is x2 + y– 2ax = 0. Find the DE of all such circles.
(ii) SolvetheDE \(\left(1+x^{2}\right) \frac{d y}{d x}+y=\tan ^{-1} x\) (March – 2010)
Answer:
Plus Two Maths Chapter Wise Previous Questions Chapter 9 Differential Equations 13
Plus Two Maths Chapter Wise Previous Questions Chapter 9 Differential Equations 14

Question 4.
(i) Solution of the DE y – y = 0 is y = ………….
(ii) Solve the DE \(\Rightarrow \frac{d y}{d x}+y \sec x=\tan x\)
(iii) Form the DE of the family of ellipse having foci on the x-axis and centre at the origin. (March-2011)
Answer:
Plus Two Maths Chapter Wise Previous Questions Chapter 9 Differential Equations 15
Plus Two Maths Chapter Wise Previous Questions Chapter 9 Differential Equations 16

Question 5.
Consider the DE \(x d y-y d x=\sqrt{x^{2}+y^{2}} d x\)
(i) Express it in the form \(\frac{d y}{d x}\) = F(x, y)
(ii) Find the general solution. (March -2012; Edumate -2017)
Answer:
Plus Two Maths Chapter Wise Previous Questions Chapter 9 Differential Equations 17
Plus Two Maths Chapter Wise Previous Questions Chapter 9 Differential Equations 18

Question 6.
(i) Prove that the DE is (3xy + y2) dx + (x2 + xy) dy = 0 a homogeneous DE of degree 0.
(ii) Solve the DE (3xy + y2) dx + (x2 + xy) dy = 0 (May —2012, Edumate -2017)
Answer:
Plus Two Maths Chapter Wise Previous Questions Chapter 9 Differential Equations 19
Plus Two Maths Chapter Wise Previous Questions Chapter 9 Differential Equations 20
Plus Two Maths Chapter Wise Previous Questions Chapter 9 Differential Equations 21

Question 7.
Consider the differential equation \(\frac{d y}{d x}-3 \cot x y=\sin 2 x\)
(a) Find its integrating factors.
(b) Fînd its solution, given that y = 2 When x = \(\frac{\pi}{2}\). (May-2014)
Answer:
Plus Two Maths Chapter Wise Previous Questions Chapter 9 Differential Equations 22
Plus Two Maths Chapter Wise Previous Questions Chapter 9 Differential Equations 23

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