Выполните действие: 1)(x-5)(x+5) 2)(8+y)(y-8) 3)(10-k)(k+10) 4)(a+2/3b)(a-2/3b) 5)(4/9x-y)(y+4/9x) 6)(4/15n-m)(m+4/15n) 7)(9x-5y)(9x+5y) +3b)(3b+4a) 9)(13k-2b)(2b+13k) 10)(5/4c+3/7d)(3/7d-5/4c) 11)(1/3x-3y)(3y+1/3x) 12)(1/5a+1/9b)(1/9b-1/5a) решите

1)(х-5)×(х+5)=х^2-25 2)(8+у)×(у-8)= -64+у^2 3)(10-к)×(к+10)=100-к^2 4)(a+2/3b)×(a-2/3b)=a^2+4/9b^2 5)(4/9x-y)×(y+4/9x)= -y^2+16/81x^2 6)(4/15n-m)×(m+4/15n)= -m^2+16/225n^2 7)(9x-5y)×(9x+5y)= 81y^2-25y^2 8)(-4a+3b)×(3b+4a)= -16a^2+9b^2 9)(13k-2b)×(2b+13k)= 169k^2-4b^2 10)(5/4c+3/7d)×(3/7d - 5/4c)= -25/16c^2+9/49d^2 11)(1/3x-3y)×(3y+1/3x)= -9y^2+1/9x^2 12)(1/5a+1/9b)×(1/9b - 1/5a)=1/25a^2+1/81b^2