(7a^2+2b^2)^2-(2b^2+7b^2)^2 =0
(a^2+b^2+c^2)^2-4a^2b^2 =（a-b+c）*（a-b-c）*（a+b-c）*（a+b+c）
(x+1)(x+2)(x+3)(x+4)-120 =(x^2+5x+16)(x+6)(x-1)
3x^2+4y^2+3z^2+8xy-8zy-10xz =(3x+2y-z)(x+2y-3z)
x^2+2(a+b)x-(3a^2-10ab+3b^2) =(x-3a+b)(x-a+3b)
6x^2+7xy+2y^2-8x-5y+2 =（2x+y-2)(3x+2y-1)
x^3+9x^2+26x+24 =(x+4)(x+2)(x+3)
a^3+b^3+c^3-3abc =(a+b+c)(a^2+b^2+c^2-ab-bc-ac)