Most Important Selected Qs for JEE AdvancedMathematicsDifferentiation
If y= x+ x+ x+ x+ , where x>0 , then d y d x can be:
Options
- A1 2 y-1
- Bx x+2 y
- C1 1+4 x
- Dy 2 x+y
Correct answer
D. y 2 x+y
Step-by-step solution
y= x+y y^2=x+y y^2-y-x=0 ...(1) (2 y-1) y^ =1 y^ = 1 2 y-1 (a) From equation (1), 2 y=1+ 1+4 x Hence, 2 y-1= 1+4 x y^ = 1 1+4 x (c) On dividing by y , equation (1) gives y-1= x y 2 y-2= 2 x y (d) : y 2 x+y = 1 2 x y +1 = 1 (2 y-2)+1 = 1 2 y-1 which is same as (a).