the highest derivative is a second derivative - and therefore there can be only two arbitrary constants of integration in the solution - and we already have two in Equation ???, and cons...the highest derivative is a second derivative - and therefore there can be only two arbitrary constants of integration in the solution - and we already have two in Equation ???, and consequently there are no further solutions. It will not take long to discover that solutions of the form y=ekx satisfy the Equation, because then y′=ky and y″=k2y, and, if you substitute these in Equation ???, you obtain