Concept:Factorising quadratic expressions to simplify a rational algebraic fraction by cancelling common factors.Explanation:Factorise the numerator: x2−5x−14=(x−7)(x+2).Factorise the denominator: x2−9x+14=(x−7)(x−2).Substitute the factors into the fraction:x2−9x+14x2−5x−14=(x−7)(x−2)(x−7)(x+2)Cancel the common factor (x−7) from the numerator and denominator:=x−2x+2This simplification is valid for x=7.Answer:x−2x+2Option D.