1.2 Factorise the following expressions fully: \( \begin{array}{l}1.2 .1 \quad 3 x-x^{2} \\ 1.2 .2\end{array} \quad y-x y+x-1 \)

To factorise the expression \( 3x - x^{2} \), we can take out the common factor from both terms. Rearranging gives us \( -x^{2} + 3x \). Factoring out \(-x\) yields: \(-x(x - 3)\). For the second expression \( y - xy + x - 1 \), we can group terms to aid in factorisation. Rearranging gives \( y(1 - x) + (x - 1) \). Recognising the factorisation tells us we can rearrange as: \((1 - x)(y + 1)\).