Manipal MET2016MathematicsApplication of Derivatives
The points on the curve x y^2=1 which are nearest to the origin, are
Options
- A[ ( 1 2 )^ 1 / 3 , ( 1 2 )^ -1 / 6 ]
- B[ ( 1 2 )^ 1 / 3 , 2^ -1 / 6 ]
- C[2^ 1 / 3 , ( 1 2 )^ -1 / 6 ]
- DNone of these
Correct answer
A. [ ( 1 2 )^ 1 / 3 , ( 1 2 )^ -1 / 6 ]
Step-by-step solution
Let P(x, y) be such a point, then O P^2=x^2+y^2 Let s=O P^2=x^2+ 1 x d s d x =2 x- 1 x^2 For maximum or minimum, put d s d x =0 2 x- 1 x^2 =0 x^3= 1 2 x= ( 1 2 )^ 1 3 Also, d^2 s d x^2 =2+ 2 x^3 Now, ( d^2 s d x^2 )_ x= ( 1 2 )^ 1 / 3 =2+ 2 1 / 2 0 s is minimum at x= ( 1 2 )^ 1 / 3 . Thus, for nearest point x= ( 1 2 )^ 1 / 3 , y= ( 1 2 )^ -1 / 6