difference equation

space

U+0020

latin small letter a

U+0061

latin small letter c

U+0063

latin small letter d

U+0064

latin small letter e

U+0065

latin small letter f

U+0066

latin small letter i

U+0069

latin small letter n

U+006E

latin small letter o

U+006F

latin small letter q

U+0071

latin small letter r

U+0072

latin small letter t

U+0074

latin small letter u

U+0075