Question

Find the order of the difference equation Δ^3yn – Δ^2yn – Δyn = 3.

(a) 3

(b) 4

(c) 2

(d) 5

The question was posed to me in a job interview.

My doubt is from Linear Difference Equations and Z in section Fourier Integral, Fourier Transforms and Integral Transforms of Engineering Mathematics

Answer 1

Right choice is (a) 3

The best I can explain: The first step is to expand the given equation by replacing every Δyn by (yn+1– yn). Order of a difference equation is given by, \(\frac{n+3-n}{1}\) which is actually 3.