1.

Solution of the differential equation `x(dy)/(dx)=y+sqrt(x^(2)+y^(2))`, isA. `x+sqrt(x^(2)+y^(2))=Cy^(2)`B. `y+sqrt(x^(2)+y^(2))=Cy^(2)`C. `x+sqrt(x^(2)+y^(2))=Cx^(2)`D. `y+sqrt(x^(2)+y^(2))=Cx^(2)`

Answer» Correct Answer - D
Substituting `y=vx and (dy)/(dx)=v+x(dv)/(dx),` we get `v+x(dv)/(dx)=v+sqrt(1+v^(2))rArr (1)/(sqrt(1+v^(2)))dv=(1)/(x)dx`
On integrating, we get
`log(v+sqrt(v^(2)+1))=logx+logC`
`rArr" "v+sqrt(v^(2)+1)=CxrArr y+sqrt(x^(2)+y^(2))=Cx^(2)`


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