MSOLVE(M,b)
MSOLVE(M, b) returns the solution of M x = b efficiently without matrix inversion. Matrix M must be a square matrix (m x m). Vector b and vector x must be of size m x 1.
In the screenshot below, the M matrix is contained in the range A1:C3 (3 rows x 3 columns), the b matrix is contained in the range E1:E3 (3 rows x 1 column) and the x matrix (3 rows x 1 column) has been entered as an array formula in the cell range G1:G3.