A relationship between two or more functions can be expressed in the form f(x) = ∫K(x, y) F(y) dy then f(x) is the integral transform of F(x), and K(x,y) is the kernel of the transform. If F(x) can be found from f(x) then the transform can be inverted. Integral transforms, such as the Fourier transform and the Laplace transform, are useful in transforming differential equations in F(x) into algebraic equations in f(x) which can then be solved, and the solution f(x) inverted to find F(x), the solution to the original problem.