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Solve : `(dy)/(dx) - (2y)/(x) = y^(4)` |
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Answer» On dividing the equation vy `y^(4)`, we have `(1)/(y^(4)) (dy)/(dx) - ((2)/(y^(3)).(1)/(x)) = 1` Set `(1)/(y^(3)) = v`, so that, `-(3)/(y^(4))(dy)/(dx) = (dv)/(dx)` Our equation reads, `-(1)/(3)(dv)/(dx) - (2v)/(x) = 1` `rArr (dv)/(dx) + (6)/(x) v = -3` which is a linear differential equation in v. `IF = e^(6int (dx)/(x)) = e^(6 ln x) = x^(6)` Multiplying the equation by IF and integrating, we get `vx^(6) = -3int x^(6) dx + k`, k being a constant of integration. `= -3 (x^(7))/(7) + k` `rArr (1)/(y^(3)) x^(6) = -(3)/(7) x^(7) + k` `rArr (3)/(7)x^(7) + (x^(6))/(y^(3)) = k` `:. x^(6)(3x+(7)/(y^(3))) = lambda, lambda` being another constant. |
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