NonCommutativeExpand

NonCommutativeExpand[expr]
NonCommutativeExpand[expr, alg]

expands non-commutative products in expr. With a second argument, multiplication, addition and algebra relations are taken from alg.

Example

NonCommutativeExpand[(a + 2 b) ** (3 a + 4 b)]

Unlike ordinary Expand, the order of factors joined by ** is preserved.

See the official Wolfram Language reference for more details.