2. (10 pts) Invert the matrix using the Armani Method, [A | | ], (Gauss-Jordan elimination via row operations). {Hint: Once augmented, multiply the middle row by 2 before using row ops} 2 6 2 7 6 21. (10 pts) The following system has infinitly many solutions. Use an augmented matrix and row operations, and finally parameters, to describe the solution set (i.e. the answer). X1 - X2+ 2X3 - X4 = -1 2X1+ X2 - 2X3 - 2X4 = -2 -1X1 + 2X2 - 4X3 + X4 = 1 3X1 - 3X4 = -35. (10 pts) If the matrix A is 3x4, B is 3x4, C is 4x2, D is 3x2, and E is 4x3, what are the dimensions of the following expressions (don't just give answers - show intermediate dimensions) (a) D (BE) (b) BD + ED (c) D + BAT