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scarlets99
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Homework Statement
Find the general solution for this differential equation.
dy −2x^2 + y^2 + x
dx = x y
Homework Equations
The Attempt at a Solution
dy/dx = (−2x^2 + y^2 + x) / (x y)
let y^2 = v
dy/dx = v + x dv/dx
v + x (dv/dx) = (-2x^2 + v^2 x^2 + x ) / v x^2
=> x (dv/dx) = (-2x^2 + v^2 x^2 + x ) / (v x^2) - (v)
=> x (dv/dx) = [ (-2x^2 + v^2 x^2 + x ) - v^2 x^2 ] / vx^2
=> x (dv/dx) = [ -2x^2 + x ] / vx^2
=> dv/dx = (-2x + 1) / vx^2
separating variables
v dv = [ (-2x + 1) / x^2 ] dx
v dv = - 2(1/x) dx + (1/x^2) dx
integrating
(1/2)v^2 = - 2 ln x - (1/x) + c
v^2 = -4 ln x - (2/x) + C
substitute v = y/x
y^2 / x^2 = -4ln x - (2/x) + C
y^2 = -4x^2 ln(x) - 2x + Cx^2
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