Выполните умножения двучленов 1) (m+n)(m-n) 2) (c-d)(d+c) 3) (x+y)(y-x) 4) (x+2)(2-x) 5) (n-2m)(n+2m) 6) (8a+9b)(9b-8a)

1) M^2-n^2
2)C^2-d^2
3) y^2-x^2
4) 4-x^2
5) n^2-4m^2
6) 81b^2-64a^2

M^2-mn+mn-n^2=m^2-n^2
cd+c^2-d^2-cd=c^2-d^2
xy-x^2+y^2-xy=x^2+y^2
2x-x^2+4-2x=4-x^2=(2-x)(2+x)
n^2+2mn-2mn-2m^2=n^2-2m^2
72ab-64a^2+81a^2-72ab=64a^2+81a^2=145a^2