(1.2с^2+d)(1.2c^2-d)=(1.2)^2 c^4-d^2=1.44c^4-d^2 (5x^2-4y^2)^2=25x^4-40x^2 y^2+16y^2 (9z^6-4y^2)^2=81z^12-72y^2 z^6+16y^4 (1+a)(a-1)=(a+1)(a-1)=a^2-1 (6x+9y^3)^2=36x^2+108xy^3+81y^6 (m-12) (m+12)=m^2-144 (2x+3y)^2=4x^2+12xy+9y^2 (2x-1)(2x+1)=4x^2-1 (1/4 x^2+y^7)(1/4x^2-y^7)=1/16x^4-y^14 (5a^8-6x^3)^2=25a^16-60a^8 x^3+36x^6 (3/7+6a)(6a-3/7)=36a^2-9/49 (x^2+m)(x^2-m)=m^2-x^4 (a^2+4)^2=a^4+8a^2+16 (x^3-2y^4)(x^3+2y^4)=x^6-4y^8 (0.1a-b)^2=0.01a^2-0.2ab+b^2 (y-5)(y+5)=y^2-25 (3y+2)^2=9y^2+12y+4 (a^2+3)(3-a^2)=9-a^4  (0.7x+y^2)(0.7x-y^2)=0.49x^2-y^4 (3y-4x)^2=9y^2-24y+16x^2 (c-2)(c+2)=c^2-4 (6+x)^2=x^2+12x+36 (y+4)(y-4)=y^2-16 (5x^2+2y^3)(5x^2-2y^3)=25x^4-4y^6 (a^3-b^2)^2=a^6-2a^3 b^2+b^4 (2a-9b)(2a+9b)=4a^2-81b^2 (a-1)(a+1)=a^2-1 (7k-1)^2=49k^2-14k+1 (4x^6-7y^9)(7y^9+4x^6)=16x^12-49y^18 (1+3k)^2=9k^2+6k+1