Problem 4: If the data points in Problem 1 were fitted into a quadratic least-squares curve Y, where Y=a0+a1x+a2x2, such that: Da=b, where the matrices: a is 31 column vector ( a0,a1,a2),D is 33 normal matrix, and b is 31 column vector, solve points (15 to 17): (15) The value of vector (b) is: a. [5,5,7.5]T b. [5,7.5,12.5]T c. [17.2,25,42.8]T d. [22.1,25,42.8]T (16) Column 2 in matrix (D) is: a. [5,5,7.5]T b. [5,7.5,12.5]T c. [7.5,12.5,22.1]T d. [17.2,25,42.8]T 7) Column 3 in matrix (D) is: a. [5,5,7.5]T b. [5,7.5,12.5]T c. [7.5,12.5,22.1]T d. [17.2,25,42.8]T