JEE Main20207 Jan 2020Morning ShiftMathematicsDifferentiationActual
Let x k + y k = a k , a , k > 0 and d y d x + y x 1 3 = 0 , then k is
Options
- A3 2
- B4 3
- C2 3
- D1 3
Correct answer
C. 2 3
Step-by-step solution
Differentiating the given equation with respect to x k . x k - 1 + k . y k - 1 d y d x = 0 ⇒ d y d x = - x y k - 1 ⇒ d y d x + x y k - 1 = 0 ⇒ k - 1 = - 1 3 ⇒ k = 1 - 1 3 = 2 3