原式=x^4+2x^2+1-25x^2 =(x^2+1)^2-(5x)^2 =(x^2+1+5x)(x^2+1-5x)第二题同上原式=x^4+2x^2+1-49x^2 =(x^2+1)^2-(7x)^2 =(x^2+1+7x)(x^2+1-7x)