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Let y^3 - y + x = 0 then \frac{\mathrm{d} y}{\mathrm{d} x} = ?

  • Option 1)

    1 - 3y^{2}

  • Option 2)

    \frac{1}{1 - 3y^{2}}

  • Option 3)

    \frac{1}{3y^{2}-1}

  • Option 4)

    3y^{2} -1

 

Answers (1)

best_answer

As we have learnt,

 

Derivative of implict function -

When  y  is given in any function then we find derivative of function first then find derivative of  y and collect the terms containing  

dy / dx  on left side and find  dy / dx in terms of  x & y

- wherein

ex:

Let \:\:y=siny

\frac{dy}{dx}=cosy\times\frac{dy}{dx}

\frac{dy}{dx}(1-cosy)=0

ex:

Let\:\:y=sin(xy)

\frac{dy}{dx}=cos(xy)\times(1.y+\frac{xdy}{dx})

\frac{dy}{dx}(1-x\:cos(xy))=y\:cos(xy)

\therefore \:\frac{dy}{dx}=\frac{y\:cos(xy)}{1-x\:cos(xy)}

 

 \frac{\mathrm{d} y^3 - y + x}{\mathrm{d} x} = 0 \Rightarrow 3y^2 \frac{\mathrm{d} y}{\mathrm{d} x} - \frac{\mathrm{d} y}{\mathrm{d} x} + 1 = 0

\Rightarrow \frac{\mathrm{d} y}{\mathrm{d} x}(3y^2 - 1) = -1 \Rightarrow \frac{\mathrm{d} y}{\mathrm{d} x} = \frac{1}{1 - 3y^2}

 


Option 1)

1 - 3y^{2}

Option 2)

\frac{1}{1 - 3y^{2}}

Option 3)

\frac{1}{3y^{2}-1}

Option 4)

3y^{2} -1

Posted by

Himanshu

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