plz solve

Find the sum of the the intercepts on the axes of coordinates by any tangent to the curve √x +√y=2

Plz solve this problem............

2 Answers

21
omkar ·

Answer is basically 4 units...
If point is (h,k), m=dy/dx=-(k/h)^(1/2)
X-intercept of tangent turns out as 2(h^{1/2})
Y-intercept = 2(k^1/2)
Adding 2(h^{1/2}+k^{1/2})=4units...

11
Joydoot ghatak ·

ya the answer is 4.

it is basically an identity...

that if the curve x + √y = √a cuts intercepts in the X and Y axes....
the sum of the intercepts is a.

it can be proved in the manner omkar has done...
x + √y = √a.
differenciating,

(dy/dx)at (h,k) = - √k/h [ (h,k) be a point on tangent]

equation of the tangent:-
-√k/h (x-h) = (y-k).

in this equation, once put x=0 ( for the intercept on x- axis) and y=0 ( for the intercept on y- axis).

then add, the two intercepts... it would sum upto a.
here √a = 2 = √4.
thus the ans is a=4.

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