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Solution of diffrential equation dy/dx= \frac{1-y}{\cos ^2x}  is  

  • Option 1)

    e^{\tan x}( y+1 )= C

  • Option 2)

    e^{ x}( y-1 )= C

  • Option 3)

    e^{\tan x}( y-1 )= C

  • Option 4)

    e^{\sin x}( y-1 )= C

 

Answers (1)

best_answer

As we have learned

Linear Differential Equation -

Multiply by e^{SPdx}  which is the Integrating factor

- wherein

P is the function of x alone

 

 \frac{dy}{dx} = \frac{1-y}{\cos ^2 x } \Rightarrow dy/dx = \sec ^2x (1-y)

\Rightarrow \frac{dy}{dx} + (\sec^2x) y = \sec^2 x

on comparing it with \frac{dy}{dx} + Py =Q , we get

 P =\sec ^2 x ..and ..Q= sec ^2 x

, so integrating factor will be e^{\int \sec^2xdx} = e^{\tan x }

multiplying on both sides , we get \rightarrow 

e^{\tan x} dy/dx + y e^{\tan x} \sec^2x = e^{\tan x} \sec ^2x

\Rightarrow d/dx (e^{\tan x } y) = e^{\tan x} \sec ^2 x

\Rightarrow d(e^{\tan x}y)- e^{\tan x} \sec^2x dx = 0

\Rightarrow \int d(e^{\tan x}y)- \int e^{\tan x} \sec^2x dx = c

\Rightarrow e^{\tan x} y - e^{\tan x}= C

\Rightarrow e^{\tan x} (y -1)= C

 

 

 

 

 


Option 1)

e^{\tan x}( y+1 )= C

Option 2)

e^{ x}( y-1 )= C

Option 3)

e^{\tan x}( y-1 )= C

Option 4)

e^{\sin x}( y-1 )= C

Posted by

gaurav

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