Question

Find the product:

(3x + 2y − 4)(x − y)

Answer 1

By column method:

$$\begin{gathered} 3\mathrm{x}+2\mathrm{y}-4 \\ \underline{\times (\mathrm{x}-\mathrm{y})} \\ 3{\mathrm{x}}^2+2\mathrm{yx}-4\mathrm{x} \\ \underline{-3\mathrm{xy}-2{\mathrm{y}}^2+4\mathrm{y}} \\ \mathrm{Add}:3{\mathrm{x}}^2-\mathrm{xy}-4\mathrm{x}+4\mathrm{y}-2{\mathrm{y}}^2 \\ \therefore (3\mathrm{x}+2\mathrm{y}-4)(\mathrm{x}-\mathrm{y})=3{\mathrm{x}}^2-\mathrm{xy}-4\mathrm{x}+4\mathrm{y}-2{\mathrm{y}}^2 \end{gathered}$$