If x = A cos 4t + B sin 4t, then d2x/dt2 Class 12th Mathematics, Question Paper 2023: If x = A cos 4t + B sin 4t, then d2x/dt2 By Rohit Sharma - March 11, 2023 These are the options for the Question: If x = A cos 4t + B sin 4t, then d2x/dt2 (a) х (b) -х (c) 16х (d) -16x The correct answer is – Therefore, the answer is (d) -16x.