When f(x) is divided by (x+1) and (x-1) , the remainders are 19 and 5 respectively . ∴ f(-1) = 19 and f(1) = 5 ⇒ (-1)4 - 2 (-1)3 + 3(-1)2 - a (-1) + b = 19 ⇒ 1 +2 + 3 + a + b = 19 ∴ a + b = 13 ------- (i) Again , f(1) = 5 ⇒ 14 - 2 × 13 + 3 × 12 - a × 1 b = 5 ⇒ 1 - 2 + 3 - a + b = 5 ∴ b - a = 3 ------ (ii) solving eqn (i) and (ii) , we get a = 5 and b = 8 Now substituting the values of a and b in f(x) , we get ∴ f(x) = x4 - 2x3 + 3x2 - 5x + 8 Now f(x) is divided by (x-3) so remainder will be f(3) ∴ f(x) = ∴ f(x) = x4 - 2x3 + 3x2 - 5x + 8 ⇒ f(3) = 34 - 2 × 33 + 3 × 32 - 5 × 3 + 8 = 81 - 54 + 27 - 15 + 8 = 47