AP EAMCET2006MathematicsDifferential Equations
If x^y=y^x , then x(x-y x) d y d x is equal to :
Options
- Ay(y-x y)
- By(y+x y)
- Cx(x+y x)
- Dx(y-x y)
Correct answer
A. y(y-x y)
Step-by-step solution
x^y=y^x Taking log on both sides, we get y x=x y On differentiating with respect to x , we get y 1 x + x d y d x =x 1 y d y d x + y (x-y x) y d y d x = -x y+y x x(x-y x) d y d x =y(-x y+y)