English

Cos 2 ( X − 2 Y ) = 1 − 2 D Y D X

Advertisements
Advertisements

Question

\[\cos^2 \left( x - 2y \right) = 1 - 2\frac{dy}{dx}\]
Sum
Advertisements

Solution

We have, 

\[ \cos^2 \left( x - 2y \right) = 1 - 2\frac{dy}{dx}\]

\[ \Rightarrow 2\frac{dy}{dx} = 1 - \cos^2 \left( x - 2y \right)\]

\[\text{Let }x - 2y = v\]

\[ \Rightarrow 1 - 2\frac{dy}{dx} = \frac{dv}{dx}\]

\[ \Rightarrow 2\frac{dy}{dx} = 1 - \frac{dv}{dx}\]

\[ \therefore 1 - \frac{dv}{dx} = 1 - \cos^2 v\]

\[ \Rightarrow \frac{dv}{dx} = \cos^2 v\]

\[ \Rightarrow \sec^2 v dv = dx\]

Integrating both sides, we get

\[\int \sec^2 v dv = \int dx\]

\[ \Rightarrow \tan v = x - C\]

\[ \Rightarrow \tan\left( x - 2y \right) = x - C\]

\[ \Rightarrow x = \tan\left( x - 2y \right) + C\]

shaalaa.com
  Is there an error in this question or solution?
Chapter 21: Differential Equations - Exercise 22.08 [Page 66]

APPEARS IN

R.D. Sharma Mathematics Volume 1 and 2 [English] Class 12
Chapter 21 Differential Equations
Exercise 22.08 | Q 6 | Page 66

RELATED QUESTIONS

\[\sqrt{1 + \left( \frac{dy}{dx} \right)^2} = \left( c\frac{d^2 y}{d x^2} \right)^{1/3}\]

Verify that y = 4 sin 3x is a solution of the differential equation \[\frac{d^2 y}{d x^2} + 9y = 0\]


Verify that y2 = 4ax is a solution of the differential equation y = x \[\frac{dy}{dx} + a\frac{dx}{dy}\]


Show that y = ax3 + bx2 + c is a solution of the differential equation \[\frac{d^3 y}{d x^3} = 6a\].

 


Show that y = ex (A cos x + B sin x) is the solution of the differential equation \[\frac{d^2 y}{d x^2} - 2\frac{dy}{dx} + 2y = 0\]


\[\frac{dy}{dx} - x \sin^2 x = \frac{1}{x \log x}\]

\[\frac{dy}{dx} = x^5 \tan^{- 1} \left( x^3 \right)\]

x cos2 y  dx = y cos2 x dy


\[\frac{dy}{dx} + \frac{\cos x \sin y}{\cos y} = 0\]

dy + (x + 1) (y + 1) dx = 0


Solve the following differential equation: 
(xy2 + 2x) dx + (x2 y + 2y) dy = 0


Solve the following differential equation:
\[y\left( 1 - x^2 \right)\frac{dy}{dx} = x\left( 1 + y^2 \right)\]

 


\[2x\frac{dy}{dx} = 5y, y\left( 1 \right) = 1\]

\[\frac{dy}{dx} = 2 e^{2x} y^2 , y\left( 0 \right) = - 1\]

\[2\left( y + 3 \right) - xy\frac{dy}{dx} = 0\], y(1) = −2

Find the particular solution of edy/dx = x + 1, given that y = 3, when x = 0.


Find the solution of the differential equation cos y dy + cos x sin y dx = 0 given that y = \[\frac{\pi}{2}\], when x = \[\frac{\pi}{2}\] 

 


In a bank principal increases 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).


\[\frac{dy}{dx}\cos\left( x - y \right) = 1\]

\[\frac{dy}{dx} = \left( x + y \right)^2\]

\[\left( x + y \right)^2 \frac{dy}{dx} = 1\]

\[\frac{dy}{dx} = \frac{y - x}{y + x}\]

2xy dx + (x2 + 2y2) dy = 0


\[\left[ x\sqrt{x^2 + y^2} - y^2 \right] dx + xy\ dy = 0\]

Solve the following initial value problem:-

\[dy = \cos x\left( 2 - y\text{ cosec }x \right)dx\]


In a culture, the bacteria count is 100000. The number is increased by 10% in 2 hours. In how many hours will the count reach 200000, if the rate of growth of bacteria is proportional to the number present?


A bank pays interest by continuous compounding, that is, by treating the interest rate as the instantaneous rate of change of principal. Suppose in an account interest accrues at 8% per year, compounded continuously. Calculate the percentage increase in such an account over one year.


The tangent at any point (x, y) of a curve makes an angle tan−1(2x + 3y) with x-axis. Find the equation of the curve if it passes through (1, 2).


Find the equation of the curve which passes through the point (3, −4) and has the slope \[\frac{2y}{x}\]  at any point (x, y) on it.


Find the equation of the curve which passes through the origin and has the slope x + 3y− 1 at any point (x, y) on it.


Integrating factor of the differential equation cos \[x\frac{dy}{dx} + y\] sin x = 1, is


The equation of the curve whose slope is given by \[\frac{dy}{dx} = \frac{2y}{x}; x > 0, y > 0\] and which passes through the point (1, 1) is


The differential equation of the ellipse \[\frac{x^2}{a^2} + \frac{y^2}{b^2} = C\] is


Choose the correct option from the given alternatives:

The solution of `1/"x" * "dy"/"dx" = tan^-1 "x"` is


Solve the following differential equation.

`y^3 - dy/dx = x dy/dx`


The integrating factor of the differential equation `dy/dx - y = x` is e−x.


Solve the differential equation:

`e^(dy/dx) = x`


Select and write the correct alternative from the given option for the question 

Differential equation of the function c + 4yx = 0 is


Given that `"dy"/"dx" = "e"^-2x` and y = 0 when x = 5. Find the value of x when y = 3.


Solve the differential equation `"dy"/"dx"` = 1 + x + y2 + xy2, when y = 0, x = 0.


Share
Notifications

Englishहिंदीमराठी


      Forgot password?
Use app×