The Equation Of The Common Tangent To The Curves y2 = 8x and xy = –1 Is   

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Question

The equation of the common tangent to the curves y2 = 8x and xy = –1 is 

 

Solution

Correct option is

y = x + 2

A point on the curve xy = –1is not the form (t, –1/t). Now

                             

∴ Equation of tangent to the curve xy = - 1 at (t, –1/t) is

                      

For this line to be tangent to the parabola y2 = 8x it should be of the form   

                           

      

Thus the required tangent is y = x + 2.

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