In [[mathematics]], '''substitution''' of [[variables]] (also called ''variable substitution'' or ''coordinate transformation'') refers to the substitution of certain variables with other variables. Though the [[study]] of how variable substitutions affect a certain [[problem]] can be interesting in itself, they are often used when solving [[mathematical]] or [[physical]] problems, as the correct substitution may greatly [[simplify]] a problem which is hard to solve in the [[original]] variables. Under certain conditions the solution to the original problem can be recovered by back-substitution (inverting the substitution). | In [[mathematics]], '''substitution''' of [[variables]] (also called ''variable substitution'' or ''coordinate transformation'') refers to the substitution of certain variables with other variables. Though the [[study]] of how variable substitutions affect a certain [[problem]] can be interesting in itself, they are often used when solving [[mathematical]] or [[physical]] problems, as the correct substitution may greatly [[simplify]] a problem which is hard to solve in the [[original]] variables. Under certain conditions the solution to the original problem can be recovered by back-substitution (inverting the substitution). |