The ODE is: y'' + 9y = 3\tan(3t) This is a linear non-homogeneous second-order ODE with constant coefficients. We can't use undetermined coefficients because $\tan(3t)$ is not a polynomial, exponential, or sine/cosine. So we use *variation of parameters*. y'' + 9y=3tan(3t) Q2dp/dt=kpand p0ek^t P=10,000 K=0.0866435 Time t=4=year Q3#(xy+y^2)dy/dx=4 first order linear equations Mc qs Degree batani thi Order Name of equations Constant solution Annihilator equation