(6a - 7)^2 - (4a - 3)^2
= (36a^2 - 84a + 49) - (16a^2 - 24a + 9= 36a^2 - 84a + 49 - 16a^2 + 24a - = 20a^2 - 60a + 40
(6a - 7)^2 - (4a - 3)^2
= (36a^2 - 84a + 49) - (16a^2 - 24a + 9
= 36a^2 - 84a + 49 - 16a^2 + 24a -
= 20a^2 - 60a + 40