Question

Find dy/dx of √x+√y=4 if y =1

Answer 1

Explanation:

In the question,

We have to find the first derivative of the equation,

√x + √y = 4

So,

Answer 2

Correct question :

Find d y / d x of √ x + √ y = 4  at  x = 1

Answer:

- 3

Explanation:

Given :

√ x + √ y = 4

= >  √ y = 4 - √ x

Squaring on both side :

= > y = ( 4 - √ x )²

Diff. w.r.t. x :

= > d y / d x = 2 ( 4 - √ x ) . ( 4 - √ x )'

= > d y / d x = 2 ( 4 - √ x ) . ( ( 4 )' - ( √ x )' )

= > d y / d x = 2 ( 4 - √ x ) . ( 0 - ( 1 / 2 √ x ) )

= >  d y / d x = - 2 ( 4 - √ x ) / 2 √ x

= >  d y / d x =  - ( 4 - √ x ) / √ x

Putting x = 1

= > f' ( 1 ) =  - ( 4 - √ 1 ) / √ 1

= >  f' ( 1 ) =  - ( 4 -  1 )

= > f' ( 1 ) = - 3

Hence we get required answer!