3x + 2y + z = -1 and 2x - y + 4z = 9 Use these equations for form a system. Reduce the corresponding augmented matrix to row echelon form. (Order the columns from x to z.) Identify the free variables from the row reduced matrix. (Select all that apply.) Ux Uy U z Use back substitution to write the variables corresponding to the leading variables in terms of the free variables. State the resulting solution. 17 X 7 E 29 7 Z What does this solution represent? O The plane perpendicular to the given planes. The two lines of intersection of the given planes. O The skew line of the given planes. O The single point of intersection of the given planes. O The line of intersection of the given planes. + t