$(2x-4)(2x+4) =$

$(xy-z)(xy+z) =$

$(x+3)(x+7) =$

$(a-1)(a+1)(a^2+1) =$

$(2x+2)(2x-2) =$

$(2x+7)(2x-4) =$

$(a-5/4)(a+5/4) =$

-(x-8)(x+8) =$

$x^4-y^4 =$

$2a^2(a^2-9) =$

$x(x-10)(x+2) =$

$x^2(x+8)(x+2) =$

$(x-2)(x+...)=... + ... - 21$

$y^2-y-6 = (y+...)(y-...)$

$bx^2+abx-5b = ... (x+...)(x-...)$

$y^4-9y^2+8y = ( ... )( ... ) ( ... )$