=8(-1/16a^4b^4+1)=8(1+a^2b^2/4)(1-a^2b^2/4)=8(1+a^2b^2/4)(1+ab/2)(1-ab/2)=1/2(4+a^2b^2)(2+ab)(2-ab)
=-1/2(a^4b^4-16)=-1/2(a^2b^2+4)(a^2b^2-4)=-1/2(a^2b^2+4)(ab+2)(ab-2)
我拍照吧。
