1.

Find the general solution of the differential equation dy/dx + y.cotx = 2x + x2.cotx

Answer»

dy/dx + y.cot x = 2x + x2 .cotx

Let P = cot x, Q = 2x + x2cot x 

I.F = e∫pdx = e∫cotxdx = e∫log(sin x) = sin x 

Sol is 

y (I.F) = ∫ (QxI.F) dx +C 

y sinx = ∫(2x + x2cotx)sin dx + c 

= ∫(2x + x2 cotx) dx +c 

= 2 ∫ x sin xdx + ∫x2 cosx dx + c 

= 2[x(-cosx)-(1)(-sinx)] +[x2 sinx - 2x(-cosx) + 2c(-sinx)] =2xcos x + 2sin x + x2sinx y sin x 

= x2 sinx + c 

This is the Required General solution for the given differential Equation.



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