16-b^2=(4-b)(4+b)
c^2-49=(c-7)(c+7)
0,04-a^2=(0,2-a)(0,2+a)
x^2-4/9=(x-2/3)(x+2/3)
4x^2-25=(2x-5)(2x+5)
81c^2-64d^2=(9c-8d)(9c+8d)
0,09x^2-0,25y^2=(0,3x-0,5y)(0,3x+0,5y)
a^2b^4-c^6d^8=(ab^2-c^3d^4)(ab^2+c^3d^4)
4a^2c^2-9x^2y^2=(2ac-3xy)(2ac+3xy)
x^24-y^22=(x^12-y^11)^2
-1600+a^12=(-40+a^6)^2
a^18-49/64=(a^9-7/9)^2