3. Consider the system of linear equations 3x1+ 12 + 403 - TA = 2x1 - 212 - 23 + 214 1 5x1 + 7x2 + 14x3 - 8x4 = 20 1 + 3x2 + 2x3 + 4x4 =-4 a) Solve this system using 4-decimal digit arithmetic with rounding, using Gaussian elimina tion method without pivoting (by hand). b) Solve this linear system applying Gaussian elimination with partial pivoting, by hand. In (b) use fractions throughout your calculations