Question

Add the following:
(i) $$\begin{gathered} x-3y-2z \\ 5x+7y-z \\ \underline{-7x-2y+4z} \\ \underline{} \end{gathered}$$

(ii) $$\begin{gathered} m^2-4m+5 \\ -2m^2+6m-6 \\ \underline{-m^2-2m-7} \\ \underline{} \end{gathered}$$

(iii) $$\begin{gathered} 2x^2-3xy+y^2 \\ -7x^2-5xy-2y^2 \\ \underline{4x^2+xy-6y^2} \\ \underline{} \end{gathered}$$

(iv) $$\begin{gathered} 4xy-5yz-7zx \\ -5xy+2yz+zx \\ \underline{-2xy-3yz+3zx} \\ \underline{} \end{gathered}$$

Answer 1

(i)
$$\begin{gathered} x-3y-2z \\ 5x+7y-z \\ \underline{-7x-2y+4z} \\ \mathbf{-}\mathbf{x}\mathbf{}\mathbf{}\mathbf{}\mathbf{+}\mathbf{2}\mathbf{y}\mathbf{}\mathbf{}\mathbf{}\mathbf{+}\mathbf{}\mathbf{}\mathbf{z} \end{gathered}$$

(ii)
$$\begin{gathered} m^2-4m+5 \\ -2m^2+6m-6 \\ \underline{-m^2-2m-7} \\ \mathbf{-}\mathbf{2}{\mathbf{m}}^{\mathbf{2}\mathbf{}\mathbf{}}\mathbf{+}\mathbf{0}\mathbf{\times }\mathbf{m}\mathbf{-}\mathbf{8} \\ \mathbf{=}\mathbf{}\mathbf{-}\mathbf{2}{\mathit{m}}^{\mathbf{2}}\mathbf{}\mathbf{}\mathbf{+}\mathbf{}\mathbf{0}\mathbf{}\mathbf{-}\mathbf{8}\mathbf{}\mathbf{=}\mathbf{}\mathbf{-}\mathbf{2}{\mathit{m}}^{\mathbf{2}}\mathbf{-}\mathbf{8} \end{gathered}$$

(iii)
$$\begin{gathered} 2x^2-3xy+y^2 \\ -7x^2-5xy-2y^2 \\ \underline{4x^2+xy-6y^2} \\ \underline{} \\ \mathbf{-}{\mathbf{x}}^{\mathbf{2}}\mathbf{-}\mathbf{7}\mathit{x}\mathit{y}\mathbf{}\mathbf{}\mathbf{-}\mathbf{7}{\mathbf{y}}^{\mathbf{2}} \end{gathered}$$

(iv)
$$\begin{gathered} 4xy-5yz-7zx \\ -5xy+2yz+zx \\ \underline{-2xy-3yz+3zx} \\ \mathbf{-}\mathbf{3}\mathbf{xy}\mathbf{}\mathbf{}\mathbf{}\mathbf{-}\mathbf{6}\mathbf{yz}\mathbf{}\mathbf{-}\mathbf{3}\mathbf{zx} \end{gathered}$$