Factorise the following expression:
121b² - 88bc + 16c²

We have  121b² - 88bc + 16c² = (11b)² - 2(11b)(4c) + (4c)²

                                        = (11b - 4c)² = (11b - 4c)(11b - 4c)

∴  121b² - 88bc + 16c² = (11b - 4c)² = (11b - 4c)(11b - 4c)