Let y be an implicit function of x defined by

Let y be an implicit function of x defined by x2x - 2xcot y - 1 = 0. Then y′(1) equals

  1. -1
  2. 1
  3. -log 2
  4. log 2

Answer

When x = 1, y = π/2

(xx – cot y)2 = cosec2 y

xx = cot y + |cosec y|

When x = 1, y = π/2

⇒ xx = cot y + cosec y

Differentiate w.r.t. to x

xx(1 + ln x) = (-cosec2 y - cosec y cot y)dy/dx

The correct option is A.