The Matrix Multiplication Puzzle


The classic equation in Linear Algebra is "A*x=b" where A is an nxn matrix, while x and b are n vectors.

The classic operation in Linear Algebra is matrix multiplication, which we can write as "A*x=?".

The classic puzzle in Linear Algebra is matrix solution, which we can write as "A*?=b".

But there is one more Linear Algebra puzzle, where the matrix A is missing. Can you determine how, given vectors x and b, to find an nxn matrix A that solves "?*x=b". As long as x is not the zero vector, there are lots of solutions, but we just need one.

I give up, show me the solution.


Last revised on 09 May 2026.