1.

हल कीजिए : `(dy)/(dx) = (x^(2) + 5xy + 4y^(2))/(x^(2))`

Answer» `(dy)/(dx) = (x^(2) + 5xy + 4y^(2))/(x^(2))" "…(i)`
यह एक समघाती अवकल समीकरण है, अतः यदि
`y = vx" "…(ii)`
`(dy)/(dx) = v + x (dv)/(dx)`
समीकरण, (i) से, `" " v + x (dv)/(dx) = (x^(2) + 5vx^(2) + 4v^(2)x^(2))/(x^(2))`
`" " = 1 + 5v + 4v^(2)`
`x(dv)/(dx) = 1 + 4v + 4v^(2) = (2v + 1)^(2)`
या `" " (dv)/((2v + 1)^(2)) = (dx)/(x)`
दोनों पक्षों में समाकलन करने पर,
`f""(dv)/((2v + 1)^(2)) = f""(dx)/(x) + c`
`(1)/(2""(2v+1)) = log x + c `
समीकरण (ii) से,
`(1)/(2(2(y)/(x)+1))=logx+c`
`(-x)/(2(x+2y))=log x + c`


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