1.

Solve (dy/dx) + y cot x = 2 cos x 

Answer»

∵ (dy/dx) + y cot x = 2 cos x

Here (dy/dx) + Py = ϕ is integral equation of linear

∴ P = cot x and ϕ = 2 cos x

I.F = e∫Pdx = e∫cot x dx

= elog(sin x) = sin x 

Now solution of differential equation is

y x I.F. = ∫ϕ x I.F dx + c

y sin x = ∫2 cos x . sin x + c

y sin x = ∫sin 2x + c

y sin x = - (cos 2x/2) + c



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