(a) (5 marks) Construct a quadrature formula with trapezoidal rule in evaluating the integral f(x) dr by using the nodes ro = a, x₁ = a+h, x2=b-h, x3 = b, where h=! -a 3 (b) (5 marks) Determine the number n, such that the quadrature formula in (a) e all elements in P₁ = {All polynomials with degree no bigger than n.}.