1.

The solution of the differential equation `(dy)/(dx) + y = 1 ( y != x)` isA. `y=ce^(x)`B. `y = ce^(-x)`C. `y = 1+ce^(x)`D. `y = 1+ce^(-x)`

Answer» Correct Answer - a
The given equation is `(dy)/(dx) +y =1`
` rArr (dy)/(dx) = 1-y rArr (dy)/(1-y) = dx`
On integrating both sides , we get
` int (dy)/(1-y) = int dx`
` rArr log.((1-y))/-1 = x+c_(1)` ,
` rArr (1-y) = e^(-xc_(1))`
`rArr 1-y = e^(-x) .e^(-c_(1))`
`rArr y = 1 +ce^(-x), "where" c = e^(-c_(1))`


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