For a real number a, let Which of the following statements are true?

I(a) = ∫ from -1 to 1 (3x² - ax + 1) dx. Split the integral: ∫3x² dx - a∫x dx + ∫1 dx over [-1, 1]. The middle term is 0 because x is an odd function on a symmetric interval. Therefore I(a) = [x³] from -1 to 1 + [x] from -1 to 1 = (1 - (-1)) + (1 - (-1)) = 2 + 2 = 4. Hence I(a) is independent of a and is always positive. The true statements are options 1 and 3.