6. Let {lo(x), 61(x), 62(I),..., 4,(x) } be the orthogonal set of Legendre polynomials over the interval (0, 1). The average value of a function f, over the interval (0, 1), is defined as f(x) dr. Prove that the average value of a Legendre polynomial 6(x) is 0 if j > 1