(p-2)^2+3p^2 = p^2 - 4p + 4 +3p^2 = 4p^2 - 4p + 4
81x^2-(9x+7y)^2= 81x^2 - 81x^2 - 126 xy - 49y^2 = - 126 xy - 49y^2
c(2c-1)^2 = c(4c^2 - 4c + 1) = 4c^# - 4c^2 + c
-4(p-2a)^2 = -4(p^2 - 4pa + 4a^2) = -4p^2 + 16 pa - 16 a^2
a(a-7)+(a+3)^2
= a^2 -7a + a^2 + 6a + 9 = 2a^2 - a + 9