1) If the I.F. of the differential equation $\frac{dy}{dx}+5y = \cos x is \int_{}^{} e^{Adx}$ then A = A) 0 B) 1 C) 3 D) 5 Answer: Option DExplanation:The I.F. of the differential equation $\frac{dy}{dx}+Py = Q$ is $e^{\int_{}^{} pdx}$ Here P = 5 therefore I.F = $e^{\int_{}^{} 5dx}$ Hence A = 5
