The x - intercept of the tangent line to a curve is equal to the ordinate of the point of contact. Find the particular curve through the point (1, 1).

Let P(x,y) be the point on the curve y = f(x) such that tangent at Pcuts the coordinate axes at A and B.

It cuts the axes at A and B so, equation of tangent at P(x,y)


Y – y = (X – x)


Now, putting Y = 0


0 – y = (X – x)


X = x – y


So, B(x – y,0)


Given, intercept on x – axis = y


x – y = y


– y = y – x



……(1)


We can see that it is a linear differential equation.


Comparing it with


P = , Q = – 1


I.F = e∫Pdy


= edy


= e – logy = y


Solution of the given equation is given by


x × I.F = ∫Q × I.F dy + c


x × = ∫ – 1 × dy + c


= – logy + c……(1)


As the equation passing through (1,1)


0 = – 1 + c


c = 1


Putting the value of c in equation (1)


= – logy + 1


x = y – ylogy


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