Now, (β−α) is maximum at β=3 and α=2. Let f(x)=−(α+β)x2+αβx+(α−β) =−5x2+6x−1 The extreme value of f(x) is calculated as, 4ac−b24a=4(−1)(−5)−624(−5) =20−36−20 =−16−20 =45