(2b + a)(2b - a)
(3x^2 + 5a^5)(3x^2 - 5a^5)
(x^2 - 16)
(4a + 4)(4a - 4)
(2ab + 3a)(2ab - 3a)
(3x+5)(3x-5)
(4x^3 - 5y^4)(4x^3 + 5y^4)
(4a^2 b^2 - 9a^2)
(9x^4 - 25a^10)
(81x^2 + 9a^2)
(49x^6 - x^8)
(a^6 - b^14)
(9x-3a)(9x+3a)
(16x^6 + 25y^8)
(7x^3 + x^4)
(9x^2 - 25)
(16a^2 - 16)
(4b^2 - a^2)
(x+4)(x-4)
(a^3 - b^7)(a^3 + b^7)