#Schrödinger's Equation
5 messages · Page 1 of 1 (latest)
Are you looking for solutions to the differential equation y'' + ky = 0?
Think about the solution to y''= 2x. If you said it was x^2, that answer is incomplete because it could have been x^2 + 5, or many other possibilities. So you write x^2 + c to account for all the possible answers.
This works the same way.
sin(x) comes from the fact that its second derivative is the negative of itself. cos(x) too. The k is there to account for the k^2 in the original equation.