1 ) Solve this Differential Equation :
2 ) Find : and
3 ) Solve in R :
1) Read this: Linear Homogeneous Ordinary Differential Equations with Constant Coefficients
2) Perhaps try the model $\displaystyle f(x) = a \cos (x) + b \sin (x)$ and solve for a and b. Is the function in 3) meant to be the same as the function in 2)?