Q18Express each of the following as the difference of two squares:
(i) (x2 - 5x + 7) (x2 + 5x + 7)
(ii) (x2 - 5x + 7) (x2 - 5x - 7)
(iii) (x2 + 5x - 7) (x2 - 5x + 7)

Solution