1) (b+3)*(b-3) = b^2-9
2) (2-x)*(2+x) = 4-x^2-x^2
3) (2c-1)*(2c+1) = 4c^2-1
4) (7x+3)*(7x-3) = 49x^2-9
5) (x+3y)*(x-3y) = x^2-9y^2
6) (2a-b)*(b+2a) = (2a-b)*(2a+b) = 4a^2-b^2
7) (y+4)*(4-y) = (4+y)*(4-y) = 16-y^2
8) (5b+1)*(1-5b) = (1+5b)*(1-5b) = 1-25b^2
9) (10a-b)*(b+10a) = (10a-b)*(10a+b) = 100a^2-b^2
10) (x^3y^2-1)*(1+x^3y^2) = (x^3y^2-1)*(x^3y^2+1) = x^9y^4-1