1. The problem statement, all variables and given/known data We have y'' + 4y' + 4y = 0 ; find the general solution. 2. Relevant equations Reduction of Order. 3. The attempt at a solution So when determining the roots of the characteristic equation, -2 was a double root, and therefore we can't simply have c1e-2t + c2e-2t. So I thought I would use reduction of order to get a second equation. However in the solution, they just left it c1e-2t + c2e-2t and I'm wondering if what I was taught to do in the case of non distinct roots was wrong, or if the solution is wrong.