If the functions Ψ₁(x, t), Ψ₂(x, t) and Ψ₃(x, t) are solutions of the Schrödinger Equation for a potential V(x, t), show that the linear combination Ψ(x, t) = c₁Ψ₁(x, t) + c₂Ψ₂(x, t) + c₃Ψ₃(x, t) is also a solution of this equation.