1) (12-d)(12+d) = 12^2 - d^2 = 144 - d^2
2) (4n-7m)(4n+7m) = 4n^2 - 49m^2
3) (3a-b^2)(b^2+3a) = 3a*b^2 + 9a - b^4 - b^2
1) (12-d)(12+d) = 12^2 - d^2 = 144 - d^2
2) (4n-7m)(4n+7m) = 4n^2 - 49m^2
3) (3a-b^2)(b^2+3a) = 3a*b^2 + 9a - b^4 - b^2