f(x) = ax2 + bx + c f′(x) = 2ax + b, f′′(x) = 2a Given, f′′( − 1) = 21 ⇒ a = 41 f′( − 1) = 1 ⇒ b − 2a = 1 ⇒ b = 23 f( − 1) = a − b + c = 2 ⇒ c = 413 Now, f(x) = 41 (x2 + 6x + 13),x ∈ [ − 1,1] f′(x) = 41 (2x + 6) = 0 ⇒ x = − 3 ∈/ [ − 1,1] f(1) = 5,f( − 1) = 2 f(x) ≤ 5 {So,} αminimum = 5