An upper bound on Jacobi polynomials

Let P"k^(^@a^,^@b^)(x) be an orthonormal Jacobi polynomial of degree k. We will establish the following inequality:[email protected]?[@d"-"1,@d"1]([email protected]"-"1)(@d"1-x)(1-x)^@a(1+x)^@bP"k^(^@a^,^@b^)(x)^2 =6,@a>[email protected]>=1+24.