۲- $(3x^2y^3 - 5z^4k^2)(3x^2y^3 + 5z^4k^2) = $

۳- $(x - 2)(x + 1)(x^2 - x + 3) = $

۴- $(x + 1)(x - 1)(x^2 + 1)(x^4 + 1)(x^8 + 1) = $

۵- $(a - 1)(a + 1)(a^2 + 3)(a^4 + 2a^2 - 3) = $

۶- $(a - 1)(a + 2)(a + 3)(a + 4) = $

۷- $(2x - 3y)^2$

۸- $(x - 1)(x + 1)(x^2 - 1)(x^4 - 2x^2 + 3) = $