1.

y×y=y2

Answer»

y2 dx = (1 - 3xy) dy 

dx/dy = 1/(y2) - 3x/y

dx/dy + 3x/y = 1/y2 

This is a first order linear differential equation of the form x' + P(y)x = Q(y) where the integrating factor = e(∫P(y) dy) = e(∫3/y dy) = y

Multiplying both sides by integrating factor: 

y3(dx/dy) + 3y2x = y 

Note that the left hand side equals d/dy[x*y^3], so: d/dy[xy3] = y 

Integrating both sides: 

xy3 = (y2)/2 + C 

x = 1/(2y) + C/(y3)



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