Factorise x squared -2x plus 3?

Despite my serious qualms with the Wording of your question, I am assuming it to be the factoring of x2-2x+3

This is not factorable. As long as there is a positive 3 in the position of the constant element, there can only be -4 or 4 for the coefficient of the single x. Perhaps you made an error in entering the question, so I will provide some likely alternatives.

If the trinomial read as x2-2x-3, then it would be factorable and would be (x-3)(x+1)

If the trinomial read as x2-4x+3, then it would be factored as (x-3)(x-1)

If the trinomial read as x2+4x+3, then it would be factored as (x+3)(x+1)