KCET2016MathematicsApplication of Derivatives
The maximum value of ( ( 1 x )^ x ) is
Options
- A( e )
- Be^ e
- C( e^ 1 e )
- D( ( 1 e )^ e )
Correct answer
C. ( e^ 1 e )
Step-by-step solution
Let ( y= ( 1 x )^ x ) Taking log on both the sides, we get [ array l y=x ( 1 x )=-x x y=-x x (1) array ] Now, differentiating Eq. (1) with respect to ( x ), we get [ array l 1 y d y d x =- (x 1 x + x ) 1 y d y d x =-(1+ x) d y d x =-y(1+ x) (2) d y d x =- ( 1 x )^ x (1+ x) array ] [ array l Now, d y d x =0 -y(1+ x)=0 x=-1 x=e⁻¹ array ] Now, differentiating Eq. (2) with respect to ( x ), we get [ array l d² y d x² =-(1+ x) d y d x - y x d² y d x² =y(1+ x)²- y x d² y d x² = ( 1 x )^ x (1+ x)²- ( 1 x )^ x 1 x At x=e⁻¹