Find and correct the errors in the following mathematical statement.
(a - 4) (a -2) = a2 - 8
Factorise: ax3y + bx2y3 + cx2yz
We have   ax3y2 = a × x × x × x × y × y
              bx2y3 = b × x × x × y × y × y
              Â
              cx2y2z = c × x × x y × y × z
Obviously, Â Â is a common factor.
∴ We get               ax3y2 = x2y2 × a × x
                           bx2y3 = x2y2 × b × y
                           cx2y2z = x2y2 × c × z ax3y2 + bx2y3 + cx2y2z = [(x2y2 × a × x) + (x2y2 × b × y) + (x2y2 × c × z)]
                                     = x2y2 [(a × x) + (b × y) + (c × z)]
                                     = x2y2(ax + by + cz)
                             Â
                         Â