(x^2+2x-3)(x^2-4)-60
=(x+3)(x-2)(x+2)(x-1)-60
=(x^2+x-6)(x^2+x-2)-60
=(x^2+x)^2-8(x^2+x)-48
=(x^2+x-12)(x^2+x+4)
=(x^2+x+4)(x+4)(x-3)