64-x^2
×^2-16y^2
a^2-y^2
4x^2-9a^2
1-4b^2
16-b^2
m^2-25b^2
1-49n^2
100-64k^2
-25x^2+16a^2​

(8-х)(8+х)

(х-4у)(х+4у)

(а-у)(а+у)

(2х-3а)(2х+3а)

(1-2b)(1+2b)

(4-b)(4+b)

(m-5b)(m+5b)

(1-7n)(1+7n)

(10-8k)(10+8k)

(5x-4a)(5x+4a)