$144\,x^2 \,- 121 = $   ?

$(144x+11)(144x-11)$ $(12x-11)^2$ $(12x+11)(12x-11)$ $(144x+121)(144x-121)$

$64\,x^2 \,- 100\,y^2 = $   ?

$(8\,x^2+10\,y^2)(8\,x^2-10\,y^2)$ $(8x-10y)^2$ $(64x+10y)(64x-10y)$ $(8x+10y)(8x-10y)$

$\,x^2 \,- 36\,y^2 = $   ?

$(x-6y)^2$ $(x+6y)(x-6y)$ $(x+36y)(x-36y)$ $(\,x^2+6\,y^2)(\,x^2-6\,y^2)$

$9 \,- 36\,x^2 = $   ?

$(9+36x)(9-36x)$ $(3-6x)^2$ $(3+36x)(3-36x)$ $(3+6x)(3-6x)$