<span>(x-5)(x+5)=x^2-25 (6-y)(6+y)=36-y^2 (a-7)(a+7)=a^2-49 (1-c)(1+c)=1-c^2 (m-4)(m+4)=m^2-16 (n-2)(n+2)=n^2-4 (x-9)(9+×)=x^2-81 (11-d)(d +11)=121-d^2 (4+b)(b-4)=b^2-16 (a+12)(12-a)=144-a^2 (c-3)(3+c)=c^2-9 (8-b)(b+8)=64-b^2 (2x-3)(2x+3)=4x^2-9 (4y-7)(4x+7)= (8a+5)(5-8a)=25-64a^2 (9c-1)(1+9c)=81c^2-1 (10+3d)(3d-10)=9d^2-100 (11x-6)(6+11x)=121x^2-36 (2m-0,7)(2m+0,7)=4m^2-0.49 (1,2-5y)(1,2+5y)=1.44-25y^2 (8n+0,6)(8n-0,6)=64n^2-0.64 (0,9p+2)(0,9p-2)=0.81p^2-4 (1,1d-8)(8+1,1d)=1.21d^2-64 (0,1a+1)(1-0,1a)=1-0.0.1a^2 (0,7x-3y)(0,7x+3y)=0.49x^2-9y^2 (1,3m-4n)(1,3m+4n)=1.69m^2-16n^2 (5a+0,4d)(0,4d-5a)=0.16d^2-25a^2 (2,5p+6q)(6q-2,5p)=36q^2-6.25p^2 (8c-2,1d)(2,1d+8c)=64c^2-4.41d^2 (0,9x+2y)(0,9x-2y)=0.81x^2-4y^2 (1/4a-0,9b)(1/4a+0,9b)=1/16a^2-0.81b^2 (2/5m-1,5n)(2/5m+1,5n)=4/25m^2-2.25n^2 (3/7x-1/2y)(3/7x+1/2y)=9/49x^2-2/4y^2 (4/9c-9/10d)(9/10d+4/9c)=16/81c^2-81/100d^2 (1/3a+6/7b)(6/7b-1/3a)=36/49b^2-1/9a^2 (1/4a-0,9b)(1/4a+0,9b)=1/16a^2-0.81b^2</span>