Which one of the following equations related to the motion of an object is NOT correct ? (Symbols carry their usual meanings)

The equations of motion for constant acceleration describe the relationship between displacement (s), initial velocity (u), final velocity (v), acceleration (a), and time (t). The standard third equation of motion is v² = u² + 2as, which can be rearranged as v² - u² = 2as. Option 3 incorrectly states u² - v² = 2as, which reverses the signs of the velocity terms. Other options are correct: Option 1 is the standard displacement formula s = ut + ½at². Option 2 is a valid rearrangement of v = u + at. Option 4 correctly represents the displacement in the nth second, derived as S(n) - S(n-1), resulting in the formula u + (a/2)(2n-1). Therefore, option 3 is the only incorrect equation among the choices provided.